Method and apparatus for performing power calibration in wireless power transfer system

ABSTRACT

A wireless power transmitter including a power conversion unit configured to transmit wireless power generated based on magnetic coupling in a power transfer phase and a control unit configured to receive, from the wireless power receiver operating at a first operating point, a first received power packet of the first operating point and a second received power packet of the first operating point based on the first received power packet of the first operating point and the second received power packet of the first operating point and configured to receive a first received power packet of the second operating point and a second received power packet of the second operating point related to power calibration and construct a second power calibration curve based on the first received power packet of the second operating point and the second received power packet of the second operating point.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/938,546, filed on Jul. 24, 2020, which is a continuation pursuant to35 U.S.C. § 119(e) of International Application PCT/KR2020/004072, withan international filing date of Mar. 25, 2020, which claims the benefitof Korean Patent Application Nos. 10-2019-0033895 filed on Mar. 25,2019, 10-2019-0057363 filed on May 16, 2019, 10-2019-0070057 filed onJun. 13, 2019 and 10-2019-0072096 filed on Jun. 18, 2019 the contents ofwhich are hereby incorporated by reference herein in their entirety.

BACKGROUND OF THE DISCLOSURE Field of the disclosure

The present disclosure relates to wireless charging and, moreparticularly, to an apparatus and method for performing powercalibration in a wireless power transfer system.

Related Art

The wireless power transfer (or transmission) technology corresponds toa technology that may wirelessly transfer (or transmit) power between apower source and an electronic device. For example, by allowing thebattery of a wireless device, such as a smartphone or a tablet PC, andso on, to be recharged by simply loading the wireless device on awireless charging pad, the wireless power transfer technique may providemore outstanding mobility, convenience, and safety as compared to theconventional wired charging environment, which uses a wired chargingconnector. Apart from the wireless charging of wireless devices, thewireless power transfer technique is raising attention as a replacementfor the conventional wired power transfer environment in diverse fields,such as electric vehicles, Bluetooth earphones, 3D glasses, diversewearable devices, household (or home) electric appliances, furniture,underground facilities, buildings, medical equipment, robots, leisure,and so on.

The wireless power transfer (or transmission) method is also referred toas a contactless power transfer method, or a no point of contact powertransfer method, or a wireless charging method. A wireless powertransfer system may be configured of a wireless power transmittersupplying electric energy by using a wireless power transfer method, anda wireless power receiver receiving the electric energy being suppliedby the wireless power transmitter and supplying the receiving electricenergy to a receiver, such as a battery cell, and so on.

The wireless power transfer technique includes diverse methods, such asa method of transferring power by using magnetic coupling, a method oftransferring power by using radio frequency (RF), a method oftransferring power by using microwaves, and a method of transferringpower by using ultrasound (or ultrasonic waves). The method that isbased on magnetic coupling is categorized as a magnetic induction methodand a magnetic resonance method. The magnetic induction methodcorresponds to a method transmitting power by using electric currentsthat are induced to the coil of the receiver by a magnetic field, whichis generated from a coil battery cell of the transmitter, in accordancewith an electromagnetic coupling between a transmitting coil and areceiving coil. The magnetic resonance method is similar to the magneticinduction method in that is uses a magnetic field. However, the magneticresonance method is different from the magnetic induction method in thatenergy is transmitted due to a concentration of magnetic fields on botha transmitting end and a receiving end, which is caused by the generatedresonance.

The wireless power transmitter and the wireless power receiver includevarious circuit components therein and configure independent devices,but since wireless power is transmitted therebetween by magneticcoupling, the wireless power transmitter and the wireless power receiverconfigure a single wireless power transfer system. However, there may bean error between transmitted power and reception power due to a changein magnetic coupling based on actual usage environments of thetransmitter (Tx) and the receiver (Rx) (magnitudes, frequencies, andduty cycles of signals applied to the wireless power transfer system,distances/position alignment between the transmitter and the receiver,etc.). Such an error may be an obstacle to elaborate foreign objectdetection (FOD).

Therefore, there is a need for a method for calibrating transmittedpower and reception power by reflecting unique characteristics of thewireless power transfer system and changes in an actual usageenvironment and performing more elaborate FOD based thereon.

SUMMARY OF THE DISCLOSURE

The present disclosure provides an apparatus and method for performingpower calibration in a wireless power transfer system.

The present disclosure also provides an apparatus and method foradaptively calibrating power in response to a load change and performingforeign object detection (FOD).

The present disclosure also provides an apparatus and method foradaptively calibrating power in response to a change in magneticcoupling between a wireless power transmitter and a wireless powerreceiver and performing FOD.

Technical objects to be achieved by the present disclosure are notlimited to the aforementioned technical objects, and other technicalobjects not described above may be evidently understood by a personhaving ordinary skill in the art to which the present disclosurepertains from the following description.

In an aspect, a wireless power transmitter includes: a power conversionunit configured to transmit, to a wireless power receiver, wirelesspower generated based on magnetic coupling in a power transfer phase;and a communication/control unit configured to receive, from thewireless power receiver, a first received power packet and a secondreceived power packet related to power calibration and construct a firstpower calibration curve based on the first received power packet and thesecond received power packet and configured to receive, from thewireless power receiver, a third received power packet and a fourthreceived power packet related to power calibration and construct asecond power calibration curve based on the third received power packetand the fourth received power packet.

In another aspect, a wireless power receiver includes: a powerconversion unit configured to receive, from a wireless powertransmitter, wireless power generated based on magnetic coupling in apower transfer phase; and a communication/control unit configured totransmit, to the wireless power transmitter, a first received powerpacket and a second received power packet related to power calibrationin a first operating mode and configured to transmit, to the wirelesspower transmitter, a third received power packet and a fourth receivedpower packet related to power calibration in a second operating mode.

In another aspect, a wireless power transmitter includes: a powerconversion unit configured to transmit, to a wireless power receiver,wireless power generated based on magnetic coupling in a power transferphase; and a communication/control unit configured to receive, from thewireless power receiver operating at a first operating point, a firstreceived power packet of the first operating point and a second receivedpower packet of the first operating point related to power calibrationand construct a first power calibration curve based on the firstreceived power packet of the first operating point and the secondreceived power packet of the first operating point and configured toreceive, from the wireless power receiver operating at a secondoperating point, a first received power packet of the second operatingpoint and a second received power packet of the second operating pointrelated to power calibration and construct a second power calibrationcurve based on the first received power packet of the second operatingpoint and the second received power packet of the second operatingpoint.

In another aspect, a wireless power receiver includes: a powerconversion unit configured to receive, from a wireless powertransmitter, wireless power generated based on magnetic coupling in apower transfer phase; and a communication/control unit configured tooperate at a first operating point and to transmit, to the wirelesspower transmitter, a first received power packet of the first operatingpoint and a second received power packet of the first operating pointrelated to power calibration and configured to transmit, to the wirelesspower transmitter, a first received power packet of a second operatingpoint and a second received power packet of the second operating pointrelated to power calibration when an operating power is switched fromthe first operating point to the second operating point.

Other specific matters of the present disclosure are included in thedetailed description and drawings.

Advantageous Effects

Transmission power and reception power are calibrated by adaptivelyresponding to a newly changed wireless charging environment and powerloss is detected based thereon, thereby enabling more sophisticated FOD.

The effects according to the present disclosure is not limited by thecontents exemplified above, and more various effects are included in thepresent disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a wireless power system (10) according toan exemplary embodiment of the present disclosure.

FIG. 2 is a block diagram of a wireless power system (10) according toanother exemplary embodiment of the present disclosure.

FIG. 3A shows an exemplary embodiment of diverse electronic devicesadopting a wireless power transfer system.

FIG. 3B shows an example of a WPC NDEF in a wireless power transfersystem.

FIG. 4A is a block diagram of a wireless power transfer system accordingto another exemplary embodiment of the present disclosure.

FIG. 4B is a diagram illustrating an example of a Bluetoothcommunication architecture to which an embodiment according to thepresent disclosure may be applied.

FIG. 4C is a block diagram illustrating a wireless power transfer systemusing BLE communication according to an example.

FIG. 4D is a block diagram illustrating a wireless power transfer systemusing BLE communication according to another example.

FIG. 5 is a state transition diagram for describing a wireless powertransfer procedure.

FIG. 6 shows a power control method according to an exemplary embodimentof the present disclosure.

FIG. 7 is a block diagram of a wireless power transmitter according toanother exemplary embodiment of the present disclosure.

FIG. 8 shows a wireless power receiver according to another exemplaryembodiment of the present disclosure.

FIG. 9 shows a communication frame structure according to an exemplaryembodiment of the present disclosure.

FIG. 10 is a structure of a sync pattern according to an exemplaryembodiment of the present disclosure.

FIG. 11 shows operation statuses of a wireless power transmitter and awireless power receiver in a shared mode according to an exemplaryembodiment of the present disclosure.

FIG. 12 is a block diagram showing a wireless charging certificateformat according to an exemplary embodiment of the present disclosure.

FIG. 13 is a capability packet structure of a wireless power transmitteraccording to an exemplary embodiment of the present disclosure.

FIG. 14 is a configuration packet structure of a wireless power receiveraccording to an exemplary embodiment of the present disclosure.

FIG. 15 shows an application-level data stream between a wireless powertransmitter and a wireless power receiver according to an example.

FIG. 16 is a flowchart illustrating a method of performing powercalibration and foreign object detection (FOD) according to anembodiment.

FIG. 17 is a format of a received power packet according to an example.

FIG. 18 is a power transfer characteristic or calibration curveaccording to an embodiment.

FIG. 19 is a power transfer characteristic or calibration curveaccording to another embodiment.

FIG. 20 is a flowchart illustrating a foreign object detection methodaccording to an embodiment.

FIG. 21 is a flowchart illustrating a method of performing powercalibration and foreign object detection (FOD) according to anotherembodiment.

FIG. 22 is a flowchart illustrating a power calibration method based ona change in coupling according to an embodiment.

FIG. 23 is a flowchart illustrating a power calibration method based ona change in coupling according to another embodiment.

FIG. 24 shows the format of a re-ping packet according to an example.

FIG. 25 is a flowchart illustrating a method of performing powercalibration and FOD according to an embodiment.

FIG. 26 is a flowchart illustrating a power calibration method based onforeign object insertion or a change in coupling according to anembodiment.

FIG. 27 is a flowchart illustrating a power calibration method based ona change in coupling or foreign object insertion according to anotherembodiment.

FIG. 28 is a power transfer characteristic or calibration curveaccording to another embodiment of the present disclosure.

FIG. 29 is a power transfer characteristic or calibration curveaccording to another embodiment of the present disclosure.

FIG. 30 is a power transfer characteristic or calibration curveaccording to another embodiment of the present disclosure.

FIG. 31 is a graph illustrating an initial power calibration curve.

FIG. 32 is a graph illustrating an extended power calibration curve.

FIG. 33 shows a method of performing FOD when Pfo is greater than orequal to a threshold value.

FIG. 34 is a graph illustrating a method of modeling a calibration curveaccording to an example.

FIG. 35 is a graph illustrating a method of modeling a calibration curveaccording to another example.

FIG. 36 is a diagram illustrating a method of configuring an initialcalibration curve according to an embodiment.

FIG. 37 shows a calibration curve obtained by updating a y intercept ofan initial calibration curve.

FIG. 38 shows a calibration curve obtained by updating a gradient and ay intercept of an initial calibration curve.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In this specification, “A or B” may refer to “only A”, “only B” or “bothA and B”. In other words, “A or B” in this specification may beinterpreted as “A and/or B”. For example, in this specification, “A, B,or C” may refer to “only A”, “only B”, “only C”, or any combination of“A, B and C”.

The slash (/) or comma used in this specification may refer to “and/or”.For example, “A/B” may refer to “A and/or B”. Accordingly, “A/B” mayrefer to “only A”, “only B”, or “both A and B”. For example, “A, B, C”may refer to “A, B, or C”.

In this specification, “at least one of A and B” may refer to “only A”,“only B”, or “both A and B”. In addition, in this specification, theexpression of “at least one of A or B” or “at least one of A and/or B”may be interpreted to be the same as “at least one of A and B”.

Also, in this specification, “at least one of A, B and C” may refer to“only A”, “only B”, “only C”, or “any combination of A, B and C”. Also,“at least one of A, B or C” or “at least one of A, B and/or C” may referto “at least one of A, B and C”.

In addition, parentheses used in the present specification may refer to“for example”. Specifically, when indicated as “control information(PDCCH)”, “PDCCH” may be proposed as an example of “controlinformation”. In other words, “control information” in thisspecification is not limited to “PDCCH”, and “PDDCH” may be proposed asan example of “control information”. In addition, even when indicated as“control information (i.e., PDCCH)”, “PDCCH” may be proposed as anexample of “control information”.

In the present specification, technical features that are individuallydescribed in one drawing may be individually or simultaneouslyimplemented. The term “wireless power”, which will hereinafter be usedin this specification, will be used to refer to an arbitrary form ofenergy that is related to an electric field, a magnetic field, and anelectromagnetic field, which is transferred (or transmitted) from awireless power transmitter to a wireless power receiver without usingany physical electromagnetic conductors. The wireless power may also bereferred to as a wireless power signal, and this may refer to anoscillating magnetic flux that is enclosed by a primary coil and asecondary coil. For example, power conversion for wirelessly chargingdevices including mobile phones, cordless phones, iPods, MP3 players,headsets, and so on, within the system will be described in thisspecification. Generally, the basic principle of the wireless powertransfer technique includes, for example, all of a method oftransferring power by using magnetic coupling, a method of transferringpower by using radio frequency (RF), a method of transferring power byusing microwaves, and a method of transferring power by using ultrasound(or ultrasonic waves).

FIG. 1 is a block diagram of a wireless power system (10) according toan exemplary embodiment of the present disclosure.

Referring to FIG. 1, the wireless power system (10) include a wirelesspower transmitter (100) and a wireless power receiver (200).

The wireless power transmitter (100) is supplied with power from anexternal power source (S) and generates a magnetic field. The wirelesspower receiver (200) generates electric currents by using the generatedmagnetic field, thereby being capable of wirelessly receiving power.

Additionally, in the wireless power system (10), the wireless powertransmitter (100) and the wireless power receiver (200) may transceive(transmit and/or receive) diverse information that is required for thewireless power transfer. Herein, communication between the wirelesspower transmitter (100) and the wireless power receiver (200) may beperformed (or established) in accordance with any one of an in-bandcommunication, which uses a magnetic field that is used for the wirelesspower transfer (or transmission), and an out-band communication, whichuses a separate communication carrier. Out-band communication may alsobe referred to as out-of-band communication. Hereinafter, out-bandcommunication will be largely described. Examples of out-bandcommunication may include NFC, Bluetooth, Bluetooth low energy (BLE),and the like.

Herein, the wireless power transmitter (100) may be provided as a fixedtype or a mobile (or portable) type. Examples of the fixed transmittertype may include an embedded type, which is embedded in in-door ceilingsor wall surfaces or embedded in furniture, such as tables, an implantedtype, which is installed in out-door parking lots, bus stops, subwaystations, and so on, or being installed in means of transportation, suchas vehicles or trains. The mobile (or portable) type wireless powertransmitter (100) may be implemented as a part of another device, suchas a mobile device having a portable size or weight or a cover of alaptop computer, and so on.

Additionally, the wireless power receiver (200) should be interpreted asa comprehensive concept including diverse home appliances and devicesthat are operated by being wirelessly supplied with power instead ofdiverse electronic devices being equipped with a battery and a powercable. Typical examples of the wireless power receiver (200) may includeportable terminals, cellular phones, smartphones, personal digitalassistants (PDAs), portable media players (PDPs), Wibro terminals,tablet PCs, phablet, laptop computers, digital cameras, navigationterminals, television, electronic vehicles (EVs), and so on.

FIG. 2 is a block diagram of a wireless power system (10) according toanother exemplary embodiment of the present disclosure.

Referring to FIG. 2, In the wireless power system (10), one wirelesspower receiver (200) or a plurality of wireless power receivers mayexist. Although it is shown in FIG. 1 that the wireless powertransmitter (100) and the wireless power receiver (200) send and receivepower to and from one another in a one-to-one correspondence (orrelationship), as shown in FIG. 2, it is also possible for one wirelesspower transmitter (100) to simultaneously transfer power to multiplewireless power receivers (200-1, 200-2, . . . , 200-M). Mostparticularly, in case the wireless power transfer (or transmission) isperformed by using a magnetic resonance method, one wireless powertransmitter (100) may transfer power to multiple wireless powerreceivers (200-1, 200-2, . . . , 200-M) by using a synchronizedtransport (or transfer) method or a time-division transport (ortransfer) method.

Additionally, although it is shown in FIG. 1 that the wireless powertransmitter (100) directly transfers (or transmits) power to thewireless power receiver (200), the wireless power system (10) may alsobe equipped with a separate wireless power transceiver, such as a relayor repeater, for increasing a wireless power transport distance betweenthe wireless power transmitter (100) and the wireless power receiver(200). In this case, power is delivered to the wireless powertransceiver from the wireless power transmitter (100), and, then, thewireless power transceiver may transfer the received power to thewireless power receiver (200).

Hereinafter, the terms wireless power receiver, power receiver, andreceiver, which are mentioned in this specification, will refer to thewireless power receiver (200). Also, the terms wireless powertransmitter, power transmitter, and transmitter, which are mentioned inthis specification, will refer to the wireless power transmitter (100).

FIG. 3a shows an exemplary embodiment of diverse electronic devicesadopting a wireless power transfer system.

As shown in FIG. 3a , the electronic devices included in the wirelesspower transfer system are sorted in accordance with the amount oftransmitted power and the amount of received power. Referring to FIG. 3,wearable devices, such as smart watches, smart glasses, head mounteddisplays (HMDs), smart rings, and so on, and mobile electronic devices(or portable electronic devices), such as earphones, remote controllers,smartphones, PDAs, tablet PCs, and so on, may adopt a low-power(approximately 5 W or less or approximately 20 W or less) wirelesscharging method.

Small-sized/Mid-sized electronic devices, such as laptop computers,robot vacuum cleaners, TV receivers, audio devices, vacuum cleaners,monitors, and so on, may adopt a mid-power (approximately 50 W or lessor approximately 200 W or less) wireless charging method. Kitchenappliances, such as mixers, microwave ovens, electric rice cookers, andso on, and personal transportation devices (or other electric devices ormeans of transportation), such as powered wheelchairs, powered kickscooters, powered bicycles, electric cars, and so on may adopt ahigh-power (approximately 2 kW or less or approximately 22 kW or less)wireless charging method.

The electric devices or means of transportation, which are describedabove (or shown in FIG. 1) may each include a wireless power receiver,which will hereinafter be described in detail. Therefore, theabove-described electric devices or means of transportation may becharged (or re-charged) by wirelessly receiving power from a wirelesspower transmitter.

Hereinafter, although the present disclosure will be described based ona mobile device adopting the wireless power charging method, this ismerely exemplary. And, therefore, it shall be understood that thewireless charging method according to the present disclosure may beapplied to diverse electronic devices.

A standard for the wireless power transfer (or transmission) includes awireless power consortium (WPC), an air fuel alliance (AFA), and a powermatters alliance (PMA).

The WPC standard defines a baseline power profile (BPP) and an extendedpower profile (EPP). The BPP is related to a wireless power transmitterand a wireless power receiver supporting a power transfer of 5 W, andthe EPP is related to a wireless power transmitter and a wireless powerreceiver supporting the transfer of a power range greater than 5 W andless than 30 W.

Diverse wireless power transmitters and wireless power receivers eachusing a different power level may be covered by each standard and may besorted by different power classes or categories.

For example, the WPC may categorize (or sort) the wireless powertransmitters and the wireless power receivers as PC-1, PC0, PC1, andPC2, and the WPC may provide a standard document (or specification) foreach power class (PC). The PC-1 standard relates to wireless powertransmitters and receivers providing a guaranteed power of less than 5W. The application of PC-1 includes wearable devices, such as smartwatches.

The PC0 standard relates to wireless power transmitters and receiversproviding a guaranteed power of 5 W. The PC0 standard includes an EPPhaving a guaranteed power ranges that extends to 30 W. Although in-band(IB) communication corresponds to a mandatory communication protocol ofPC0, out-of-band (OB) communication that is used as an optional backupchannel may also be used for PC0. The wireless power receiver may beidentified by setting up an OB flag, which indicates whether or not theOB is supported, within a configuration packet. A wireless powertransmitter supporting the OB may enter an OB handover phase bytransmitting a bit-pattern for an OB handover as a response to theconfiguration packet. The response to the configuration packet maycorrespond to an NAK, an ND, or an 8-bit pattern that is newly defined.The application of the PC0 includes smartphones.

The PC1 standard relates to wireless power transmitters and receiversproviding a guaranteed power ranging from 30 W to 150 W. OB correspondsto a mandatory communication channel for PC1, and IB is used forinitialization and link establishment to OB. The wireless powertransmitter may enter an OB handover phase by transmitting a bit-patternfor an OB handover as a response to the configuration packet. Theapplication of the PC1 includes laptop computers or power tools.

The PC2 standard relates to wireless power transmitters and receiversproviding a guaranteed power ranging from 200 W to 2 kW, and itsapplication includes kitchen appliances.

As described above, the PCs may be differentiated in accordance with therespective power levels. And, information on whether or not thecompatibility between the same PCs is supported may be optional ormandatory. Herein, the compatibility between the same PCs indicates thatpower transfer/reception between the same PCs is possible. For example,in case a wireless power transmitter corresponding to PC x is capable ofperforming charging of a wireless power receiver having the same PC x,it may be understood that compatibility is maintained between the samePCs. Similarly, compatibility between different PCs may also besupported. Herein, the compatibility between different PCs indicatesthat power transfer/reception between different PCs is also possible.For example, in case a wireless power transmitter corresponding to PC xis capable of performing charging of a wireless power receiver having PCy, it may be understood that compatibility is maintained between thedifferent PCs.

The support of compatibility between PCs corresponds to an extremelyimportant issue in the aspect of user experience and establishment ofinfrastructure. Herein, however, diverse problems, which will bedescribed below, exist in maintaining the compatibility between PCs.

In case of the compatibility between the same PCs, for example, in caseof a wireless power receiver using a lap-top charging method, whereinstable charging is possible only when power is continuously transferred,even if its respective wireless power transmitter has the same PC, itmay be difficult for the corresponding wireless power receiver to stablyreceive power from a wireless power transmitter of the power toolmethod, which transfers power non-continuously. Additionally, in case ofthe compatibility between different PCs, for example, in case a wirelesspower transmitter having a minimum guaranteed power of 200 W transferspower to a wireless power receiver having a maximum guaranteed power of5 W, the corresponding wireless power receiver may be damaged due to anovervoltage. As a result, it may be inappropriate (or difficult) to usethe PS as an index/reference standard representing/indicating thecompatibility.

Wireless power transmitters and receivers may provide a very convenientuser experience and interface (UX/UI). That is, a smart wirelesscharging service may be provided, and the smart wireless chargingservice may be implemented based on a UX/UI of a smartphone including awireless power transmitter. For these applications, an interface betweena processor of a smartphone and a wireless charging receiver allows for“drop and play” two-way communication between the wireless powertransmitter and the wireless power receiver.

As an example, a user may experience a smart wireless charging servicein a hotel. When the user enters a hotel room and puts a smartphone on awireless charger in the room, the wireless charger transmits wirelesspower to the smartphone and the smartphone receives wireless power. Inthis process, the wireless charger transmits information on the smartwireless charging service to the smartphone. When it is detected thatthe smartphone is located on the wireless charger, when it is detectedthat wireless power is received, or when the smartphone receivesinformation on the smart wireless charging service from the wirelesscharger, the smartphone enters a state of inquiring the user aboutagreement (opt-in) of supplemental features. To this end, the smartphonemay display a message on a screen in a manner with or without an alarmsound. An example of the message may include the phrase “Welcome to ###hotel. Select” Yes “to activate smart charging functions: Yes I NoThanks.” The smartphone receives an input from the user who selects Yesor No Thanks, and performs a next procedure selected by the user. If Yesis selected, the smartphone transmits corresponding information to thewireless charger. The smartphone and the wireless charger perform thesmart charging function together.

The smart wireless charging service may also include receiving WiFicredentials auto-filled. For example, the wireless charger transmits theWiFi credentials to the smartphone, and the smartphone automaticallyinputs the WiFi credentials received from the wireless charger byrunning an appropriate application.

The smart wireless charging service may also include running a hotelapplication that provides hotel promotions or obtaining remotecheck-in/check-out and contact information.

As another example, the user may experience the smart wireless chargingservice in a vehicle. When the user gets in the vehicle and puts thesmartphone on the wireless charger, the wireless charger transmitswireless power to the smartphone and the smartphone receives wirelesspower. In this process, the wireless charger transmits information onthe smart wireless charging service to the smartphone. When it isdetected that the smartphone is located on the wireless charger, whenwireless power is detected to be received, or when the smartphonereceives information on the smart wireless charging service from thewireless charger, the smartphone enters a state of inquiring the userabout checking identity.

In this state, the smartphone is automatically connected to the vehiclevia WiFi and/or Bluetooth. The smartphone may display a message on thescreen in a manner with or without an alarm sound. An example of themessage may include a phrase of “Welcome to your car. Select “Yes” tosynch device with in-car controls: Yes|No Thanks.” Upon receiving theuser's input to select Yes or No Thanks, the smartphone performs a nextprocedure selected by the user. If Yes is selected, the smartphonetransmits corresponding information to the wireless charger. Inaddition, the smartphone and the wireless charger may run an in-vehiclesmart control function together by driving in-vehicleapplication/display software. The user may enjoy the desired music andcheck a regular map location. The in-vehicle applications/displaysoftware may include an ability to provide synchronous access forpassers-by.

As another example, the user may experience smart wireless charging athome. When the user enters the room and puts the smartphone on thewireless charger in the room, the wireless charger transmits wirelesspower to the smartphone and the smartphone receives wireless power. Inthis process, the wireless charger transmits information on the smartwireless charging service to the smartphone. When it is detected thatthe smartphone is located on the wireless charger, when wireless poweris detected to be received, or when the smartphone receives informationon the smart wireless charging service from the wireless charger, thesmartphone enters a state of inquiring the user about agreement (opt-in)of supplemental features. To this end, the smartphone may display amessage on the screen in a manner with or without an alarm sound. Anexample of the message may include a phrase such as “Hi xxx, Would youlike to activate night mode and secure the building?: Yes|No Thanks.”The smartphone receives a user input to select Yes or No Thanks andperforms a next procedure selected by the user. If Yes is selected, thesmartphone transmits corresponding information to the wireless charger.The smartphones and the wireless charger may recognize at least user'spattern and recommend the user to lock doors and windows, turn offlights, or set an alarm.

Hereinafter, ‘profiles’ will be newly defined based on indexes/referencestandards representing/indicating the compatibility. More specifically,it may be understood that by maintaining compatibility between wirelesspower transmitters and receivers having the same ‘profile’, stable powertransfer/reception may be performed, and that power transfer/receptionbetween wireless power transmitters and receivers having different‘profiles’ cannot be performed. The ‘profiles’ may be defined inaccordance with whether or not compatibility is possible and/or theapplication regardless of (or independent from) the power class.

For example, the profile may be sorted into 3 different categories, suchas i) Mobile, ii) Power tool and iii) Kitchen.

For another example, the profile may be sorted into 4 differentcategories, such as i) Mobile, ii) Power tool, iii) Kitchen, and iv)Wearable.

In case of the ‘Mobile’ profile, the PC may be defined as PC0 and/orPC1, the communication protocol/method may be defined as IB and OBcommunication, and the operation frequency may be defined as 87 to 205kHz, and smartphones, laptop computers, and so on, may exist as theexemplary application.

In case of the ‘Power tool’ profile, the PC may be defined as PC1, thecommunication protocol/method may be defined as IB communication, andthe operation frequency may be defined as 87 to 145 kHz, and powertools, and so on, may exist as the exemplary application.

In case of the ‘Kitchen’ profile, the PC may be defined as PC2, thecommunication protocol/method may be defined as NFC-based communication,and the operation frequency may be defined as less than 100 kHz, andkitchen/home appliances, and so on, may exist as the exemplaryapplication.

In the case of power tools and kitchen profiles, NFC communication maybe used between the wireless power transmitter and the wireless powerreceiver. The wireless power transmitter and the wireless power receivermay confirm that they are NFC devices with each other by exchanging WPCNFC data exchange profile format (NDEF).

FIG. 3B shows an example of a WPC NDEF in a wireless power transfersystem.

Referring to FIG. 3B, the WPC NDEF may include, for example, anapplication profile field (e.g., 1B), a version field (e.g., 1B), andprofile specific data (e.g., 1B). The application profile fieldindicates whether the corresponding device is i) mobile and computing,ii) power tool, and iii) kitchen, and an upper nibble in the versionfield indicates a major version and a lower nibble indicates a minorversion. In addition, profile-specific data defines content for thekitchen.

In case of the ‘Wearable’ profile, the PC may be defined as PC-1, thecommunication protocol/method may be defined as IB communication, andthe operation frequency may be defined as 87 to 205 kHz, and wearabledevices that are worn by the users, and so on, may exist as theexemplary application.

It may be mandatory to maintain compatibility between the same profiles,and it may be optional to maintain compatibility between differentprofiles.

The above-described profiles (Mobile profile, Power tool profile,Kitchen profile, and Wearable profile) may be generalized and expressedas first to nth profile, and a new profile may be added/replaced inaccordance with the WPC standard and the exemplary embodiment.

In case the profile is defined as described above, the wireless powertransmitter may optionally perform power transfer only to the wirelesspower receiving corresponding to the same profile as the wireless powertransmitter, thereby being capable of performing a more stable powertransfer. Additionally, since the load (or burden) of the wireless powertransmitter may be reduced and power transfer is not attempted to awireless power receiver for which compatibility is not possible, therisk of damage in the wireless power receiver may be reduced.

PC1 of the ‘Mobile’ profile may be defined by being derived from anoptional extension, such as OB, based on PC0. And, the ‘Power tool’profile may be defined as a simply modified version of the PC1 ‘Mobile’profile. Additionally, up until now, although the profiles have beendefined for the purpose of maintaining compatibility between the sameprofiles, in the future, the technology may be evolved to a level ofmaintaining compatibility between different profiles. The wireless powertransmitter or the wireless power receiver may notify (or announce) itsprofile to its counterpart by using diverse methods.

In the AFA standard, the wireless power transmitter is referred to as apower transmitting unit (PTU), and the wireless power receiver isreferred to as a power receiving unit (PRU). And, the PTU is categorizedto multiple classes, as shown in Table 1, and the PRU is categorized tomultiple classes, as shown in Table 2.

TABLE 1 Minimum value for a Minimum category maximum number of PTUP_(TX)_IN_MAX support requirement supported devices Class 1  2 W 1xCategory 1 1x Category 1 Class 2 10 W 1x Category 3 2x Category 2 Class3 16 W 1x Category 4 2x Category 3 Class 4 33 W 1x Category 5 3xCategory 3 Class 5 50 W 1x Category 6 4x Category 3 Class 6 70 W 1xCategory 7 5x Category 3

TABLE 2 PRU P_(RX)_OUT_MAX′ Exemplary application Category 1 TBDBluetooth headset Category 2 3.5 W Feature phone Category 3 6.5 WSmartphone Category 4  13 W Tablet PC, Phablet Category 5  25 W Smallform factor laptop Category 6 37.5 W  General laptop Category 7  50 WHome appliance

As shown in Table 1, a maximum output power capability of Class n PTUmay be equal to or greater than the P_(TX_IN_MAX) of the correspondingclass. The PRU cannot draw a power that is higher than the power levelspecified in the corresponding category.

FIG. 4a is a block diagram of a wireless power transfer system accordingto another exemplary embodiment of the present disclosure.

Referring to FIG. 4a , the wireless power transfer system (10) includesa mobile device (450), which wirelessly receives power, and a basestation (400), which wirelessly transmits power.

As a device providing induction power or resonance power, the basestation (400) may include at least one of a wireless power transmitter(100) and a system unit (405). The wireless power transmitter (100) maytransmit induction power or resonance power and may control thetransmission. The wireless power transmitter (100) may include a powerconversion unit (110) converting electric energy to a power signal bygenerating a magnetic field through a primary coil (or primary coils),and a communications & control unit (120) controlling the communicationand power transfer between the wireless power receiver (200) in order totransfer power at an appropriate (or suitable) level. The system unit(405) may perform input power provisioning, controlling of multiplewireless power transmitters, and other operation controls of the basestation (400), such as user interface control.

The primary coil may generate an electromagnetic field by using analternating current power (or voltage or current). The primary coil issupplied with an alternating current power (or voltage or current) of aspecific frequency, which is being outputted from the power conversionunit (110). And, accordingly, the primary coil may generate a magneticfield of the specific frequency. The magnetic field may be generated ina non-radial shape or a radial shape. And, the wireless power receiver(200) receives the generated magnetic field and then generates anelectric current. In other words, the primary coil wirelessly transmitspower.

In the magnetic induction method, a primary coil and a secondary coilmay have randomly appropriate shapes. For example, the primary coil andthe secondary coil may correspond to copper wire being wound around ahigh-permeability formation, such as ferrite or a non-crystalline metal.The primary coil may also be referred to as a transmitting coil, aprimary core, a primary winding, a primary loop antenna, and so on.Meanwhile, the secondary coil may also be referred to as a receivingcoil, a secondary core, a secondary winding, a secondary loop antenna, apickup antenna, and so on.

In case of using the magnetic resonance method, the primary coil and thesecondary coil may each be provided in the form of a primary resonanceantenna and a secondary resonance antenna. The resonance antenna mayhave a resonance structure including a coil and a capacitor. At thispoint, the resonance frequency of the resonance antenna may bedetermined by the inductance of the coil and a capacitance of thecapacitor. Herein, the coil may be formed to have a loop shape. And, acore may be placed inside the loop. The core may include a physicalcore, such as a ferrite core, or an air core.

The energy transmission (or transfer) between the primary resonanceantenna and the second resonance antenna may be performed by a resonancephenomenon occurring in the magnetic field. When a near fieldcorresponding to a resonance frequency occurs in a resonance antenna,and in case another resonance antenna exists near the correspondingresonance antenna, the resonance phenomenon refers to a highly efficientenergy transfer occurring between the two resonance antennas that arecoupled with one another. When a magnetic field corresponding to theresonance frequency is generated between the primary resonance antennaand the secondary resonance antenna, the primary resonance antenna andthe secondary resonance antenna resonate with one another. And,accordingly, in a general case, the magnetic field is focused toward thesecond resonance antenna at a higher efficiency as compared to a casewhere the magnetic field that is generated from the primary antenna isradiated to a free space. And, therefore, energy may be transferred tothe second resonance antenna from the first resonance antenna at a highefficiency. The magnetic induction method may be implemented similarlyto the magnetic resonance method. However, in this case, the frequencyof the magnetic field is not required to be a resonance frequency.Nevertheless, in the magnetic induction method, the loops configuringthe primary coil and the secondary coil are required to match oneanother, and the distance between the loops should be very close-ranged.

Although it is not shown in the drawing, the wireless power transmitter(100) may further include a communication antenna. The communicationantenna may transmit and/or receive a communication signal by using acommunication carrier apart from the magnetic field communication. Forexample, the communication antenna may transmit and/or receivecommunication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE,ZigBee, NFC, and so on.

The communications & control unit (120) may transmit and/or receiveinformation to and from the wireless power receiver (200). Thecommunications & control unit (120) may include at least one of an IBcommunication module and an OB communication module.

The IB communication module may transmit and/or receive information byusing a magnetic wave, which uses a specific frequency as its centerfrequency. For example, the communications & control unit (120) mayperform in-band (IB) communication by transmitting communicationinformation on the operating frequency of wireless power transferthrough the primary coil or by receiving communication information onthe operating frequency through the primary coil. At this point, thecommunications & control unit (120) may load information in the magneticwave or may interpret the information that is carried by the magneticwave by using a modulation scheme, such as binary phase shift keying(BPSK), Frequency Shift Keying(FSK) or amplitude shift keying (ASK), andso on, or a coding scheme, such as Manchester coding ornon-return-to-zero level (NZR-L) coding, and so on. By using theabove-described IB communication, the communications & control unit(120) may transmit and/or receive information to distances of up toseveral meters at a data transmission rate of several kbps.

The OB communication module may also perform out-of-band communicationthrough a communication antenna. For example, the communications &control unit (120) may be provided to a near field communication module.Examples of the near field communication module may includecommunication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee,NFC, and so on.

The communications & control unit (120) may control the overalloperations of the wireless power transmitter (100). The communications &control unit (120) may perform calculation and processing of diverseinformation and may also control each configuration element of thewireless power transmitter (100).

The communications & control unit (120) may be implemented in a computeror a similar device as hardware, software, or a combination of the same.When implemented in the form of hardware, the communications & controlunit (120) may be provided as an electronic circuit performing controlfunctions by processing electrical signals. And, when implemented in theform of software, the communications & control unit (120) may beprovided as a program that operates the communications & control unit(120).

By controlling the operating point, the communications & control unit(120) may control the transmitted power. The operating point that isbeing controlled may correspond to a combination of a frequency (orphase), a duty cycle, a duty ratio, and a voltage amplitude. Thecommunications & control unit (120) may control the transmitted power byadjusting any one of the frequency (or phase), the duty cycle, the dutyratio, and the voltage amplitude. Additionally, the wireless powertransmitter (100) may supply a consistent level of power, and thewireless power receiver (200) may control the level of received power bycontrolling the resonance frequency.

The mobile device (450) includes a wireless power receiver (200)receiving wireless power through a secondary coil, and a load (455)receiving and storing the power that is received by the wireless powerreceiver (200) and supplying the received power to the device.

The wireless power receiver (200) may include a power pick-up unit (210)and a communications & control unit (220). The power pick-up unit (210)may receive wireless power through the secondary coil and may convertthe received wireless power to electric energy. The power pick-up unit(210) rectifies the alternating current (AC) signal, which is receivedthrough the secondary coil, and converts the rectified signal to adirect current (DC) signal. The communications & control unit (220) maycontrol the transmission and reception of the wireless power (transferand reception of power).

The secondary coil may receive wireless power that is being transmittedfrom the wireless power transmitter (100). The secondary coil mayreceive power by using the magnetic field that is generated in theprimary coil. Herein, in case the specific frequency corresponds aresonance frequency, magnetic resonance may occur between the primarycoil and the secondary coil, thereby allowing power to be transferredwith greater efficiency.

Although it is not shown in FIG. 4a , the communications & control unit(220) may further include a communication antenna. The communicationantenna may transmit and/or receive a communication signal by using acommunication carrier apart from the magnetic field communication. Forexample, the communication antenna may transmit and/or receivecommunication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE,ZigBee, NFC, and so on.

The communications & control unit (220) may transmit and/or receiveinformation to and from the wireless power transmitter (100). Thecommunications & control unit (220) may include at least one of an IBcommunication module and an OB communication module.

The IB communication module may transmit and/or receive information byusing a magnetic wave, which uses a specific frequency as its centerfrequency. For example, the communications & control unit (220) mayperform IB communication by loading information in the magnetic wave andby transmitting the information through the secondary coil or byreceiving a magnetic wave carrying information through the secondarycoil. At this point, the communications & control unit (120) may loadinformation in the magnetic wave or may interpret the information thatis carried by the magnetic wave by using a modulation scheme, such asbinary phase shift keying (BPSK), Frequency Shift Keying(FSK) oramplitude shift keying (ASK), and so on, or a coding scheme, such asManchester coding or non-return-to-zero level (NZR-L) coding, and so on.By using the above-described IB communication, the communications &control unit (220) may transmit and/or receive information to distancesof up to several meters at a data transmission rate of several kbps.

The OB communication module may also perform out-of-band communicationthrough a communication antenna. For example, the communications &control unit (220) may be provided to a near field communication module.

Examples of the near field communication module may includecommunication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee,NFC, and so on.

The communications & control unit (220) may control the overalloperations of the wireless power receiver (200). The communications &control unit (220) may perform calculation and processing of diverseinformation and may also control each configuration element of thewireless power receiver (200).

The communications & control unit (220) may be implemented in a computeror a similar device as hardware, software, or a combination of the same.When implemented in the form of hardware, the communications & controlunit (220) may be provided as an electronic circuit performing controlfunctions by processing electrical signals. And, when implemented in theform of software, the communications & control unit (220) may beprovided as a program that operates the communications & control unit(220).

When the communication/control circuit 120 and the communication/controlcircuit 220 are Bluetooth or Bluetooth LE as an OB communication moduleor a short-range communication module, the communication/control circuit120 and the communication/control circuit 220 may each be implementedand operated with a communication architecture as shown in FIG. 4B.

FIG. 4B is a diagram illustrating an example of a Bluetoothcommunication architecture to which an embodiment according to thepresent disclosure may be applied.

Referring to FIG. 4B, (a) of FIG. 4B shows an example of a protocolstack of Bluetooth basic rate (BR)/enhanced data rate (EDR) supportingGATT, and (b) shows an example of Bluetooth low energy (BLE) protocolstack.

Specifically, as shown in (a) of FIG. 4B, the Bluetooth BR/EDR protocolstack may include an upper control stack 460 and a lower host stack 470based on a host controller interface (HCI) 18.

The host stack (or host module) 470 refers to hardware for transmittingor receiving a Bluetooth packet to or from a wirelesstransmission/reception module which receives a Bluetooth signal of 2.4GHz, and the controller stack 460 is connected to the Bluetooth moduleto control the Bluetooth module and perform an operation.

The host stack 470 may include a BR/EDR PHY layer 12, a BR/EDR basebandlayer 14, and a link manager layer 16.

The BR/EDR PHY layer 12 is a layer that transmits and receives a 2.4 GHzradio signal, and in the case of using Gaussian frequency shift keying(GFSK) modulation, the BR/EDR PHY layer 12 may transmit data by hopping79 RF channels.

The BR/EDR baseband layer 14 serves to transmit a digital signal,selects a channel sequence for hopping 1400 times per second, andtransmits a time slot with a length of 625 us for each channel.

The link manager layer 16 controls an overall operation (link setup,control, security) of Bluetooth connection by utilizing a link managerprotocol (LMP).

The link manager layer 16 may perform the following functions.

-   -   Performs ACL/SCO logical transport, logical link setup, and        control.    -   Detach: It interrupts connection and informs a counterpart        device about a reason for the interruption.    -   Performs power control and role switch.    -   Performs security (authentication, pairing, encryption)        function.

The host controller interface layer 18 provides an interface between ahost module and a controller module so that a host provides commands anddata to the controller and the controller provides events and data tothe host.

The host stack (or host module, 470) includes a logical link control andadaptation protocol (L2CAP) 21, an attribute protocol 22, a genericattribute profile (GATT) 23, a generic access profile (GAP) 24, and aBR/EDR profile 25.

The logical link control and adaptation protocol (L2CAP) 21 may provideone bidirectional channel for transmitting data to a specific protocolor profile.

The L2CAP 21 may multiplex various protocols, profiles, etc., providedfrom upper Bluetooth.

L2CAP of Bluetooth BR/EDR uses dynamic channels, supports protocolservice multiplexer, retransmission, streaming mode, and providessegmentation and reassembly, per-channel flow control, and errorcontrol.

The generic attribute profile (GATT) 23 may be operable as a protocolthat describes how the attribute protocol 22 is used when services areconfigured. For example, the generic attribute profile 23 may beoperable to specify how ATT attributes are grouped together intoservices and may be operable to describe features associated withservices.

Accordingly, the generic attribute profile 23 and the attributeprotocols (ATT) 22 may use features to describe device's state andservices, how features are related to each other, and how they are used.

The attribute protocol 22 and the BR/EDR profile 25 define a service(profile) using Bluetooth BR/EDR and an application protocol forexchanging these data, and the generic access profile (GAP) 24 definesdevice discovery, connectivity, and security level.

As shown in (b) of FIG. 4B, the Bluetooth LE protocol stack includes acontroller stack 480 operable to process a wireless device interfaceimportant in timing and a host stack 490 operable to process high leveldata.

First, the controller stack 480 may be implemented using a communicationmodule that may include a Bluetooth wireless device, for example, aprocessor module that may include a processing device such as amicroprocessor.

The host stack 490 may be implemented as a part of an OS running on aprocessor module or as an instantiation of a package on the OS.

In some cases, the controller stack and the host stack may be run orexecuted on the same processing device in a processor module.

The controller stack 480 includes a physical layer (PHY) 32, a linklayer 34, and a host controller interface 36.

The physical layer (PHY, wireless transmission/reception module) 32 is alayer that transmits and receives a 2.4 GHz radio signal and usesGaussian frequency shift keying (GFSK) modulation and a frequencyhopping scheme including 40 RF channels.

The link layer 34, which serves to transmit or receive Bluetoothpackets, creates connections between devices after performingadvertising and scanning functions using 3 advertising channels andprovides a function of exchanging data packets of up to 257 bytesthrough 37 data channels.

The host stack includes a generic access profile (GAP) 45, a logicallink control and adaptation protocol (L2CAP, 41), a security manager(SM) 42, and an attribute protocol (ATT) 43, a generic attribute profile(GATT) 44, a generic access profile 45, and an LE profile 46. However,the host stack 490 is not limited thereto and may include variousprotocols and profiles.

The host stack multiplexes various protocols, profiles, etc., providedfrom upper Bluetooth using L2CAP.

First, the logical link control and adaptation protocol (L2CAP) 41 mayprovide one bidirectional channel for transmitting data to a specificprotocol or profile.

The L2CAP 41 may be operable to multiplex data between higher layerprotocols, segment and reassemble packages, and manage multicast datatransmission.

In Bluetooth LE, three fixed channels (one for signaling CH, one forsecurity manager, and one for attribute protocol) are basically used.Also, a dynamic channel may be used as needed.

Meanwhile, a basic channel/enhanced data rate (BR/EDR) uses a dynamicchannel and supports protocol service multiplexer, retransmission,streaming mode, and the like.

The security manager (SM) 42 is a protocol for authenticating devicesand providing key distribution.

The attribute protocol (ATT) 43 defines a rule for accessing data of acounterpart device in a server-client structure. The ATT has thefollowing 6 message types (request, response, command, notification,indication, confirmation).

{circle around (1)} Request and Response message: A request message is amessage for requesting specific information from the client device tothe server device, and the response message is a response message to therequest message, which is a message transmitted from the server deviceto the client device.

{circle around (2)} Command message: It is a message transmitted fromthe client device to the server device in order to indicate a command ofa specific operation. The server device does not transmit a responsewith respect to the command message to the client device.

{circle around (3)} Notification message: It is a message transmittedfrom the server device to the client device in order to notify an event,or the like. The client device does not transmit a confirmation messagewith respect to the notification message to the server device.

{circle around (4)} Indication and confirmation message: It is a messagetransmitted from the server device to the client device in order tonotify an event, or the like. Unlike the notification message, theclient device transmits a confirmation message regarding the indicationmessage to the server device.

In the present disclosure, when the GATT profile using the attributeprotocol (ATT) 43 requests long data, a value regarding a data length istransmitted to allow a client to clearly know the data length, and acharacteristic value may be received from a server by using a universalunique identifier (UUID).

The generic access profile (GAP) 45, a layer newly implemented for theBluetooth LE technology, is used to select a role for communicationbetween Bluetooth LED devices and to control how a multi-profileoperation takes place.

Also, the generic access profile (GAP) 45 is mainly used for devicediscovery, connection generation, and security procedure part, defines ascheme for providing information to a user, and defines types ofattributes as follows.

{circle around (1)} Service: It defines a basic operation of a device bya combination of behaviors related to data

{circle around (2)} Include: It defines a relationship between services

{circle around (3)} Characteristics: It is a data value used in a server

{circle around (4)} Behavior: It is a format that may be read by acomputer defined by a UUID (value type).

The LE profile 46, including profiles dependent upon the GATT, is mainlyapplied to a Bluetooth LE device. The LE profile 46 may include, forexample, Battery, Time, FindMe, Proximity, Time, Object DeliveryService, and the like, and details of the GATT-based profiles are asfollows.

{circle around (1)} Battery: Battery information exchanging method

{circle around (2)} Time: Time information exchanging method

{circle around (3)} FindMe: Provision of alarm service according todistance

{circle around (4)} Proximity: Battery information exchanging method

{circle around (5)} Time: Time information exchanging method

The generic attribute profile (GATT) 44 may operate as a protocoldescribing how the attribute protocol (ATT) 43 is used when services areconfigured. For example, the GATT 44 may operate to define how ATTattributes are grouped together with services and operate to describefeatures associated with services.

Thus, the GATT 44 and the ATT 43 may use features in order to describestatus and services of a device and describe how the features arerelated and used.

Hereinafter, procedures of the Bluetooth low energy (BLE) technologywill be briefly described.

The BLE procedure may be classified as a device filtering procedure, anadvertising procedure, a scanning procedure, a discovering procedure,and a connecting procedure.

Device Filtering Procedure

The device filtering procedure is a method for reducing the number ofdevices performing a response with respect to a request, indication,notification, and the like, in the controller stack.

When requests are received from all the devices, it is not necessary torespond thereto, and thus, the controller stack may perform control toreduce the number of transmitted requests to reduce power consumption.

An advertising device or scanning device may perform the devicefiltering procedure to limit devices for receiving an advertisingpacket, a scan request or a connection request.

Here, the advertising device refers to a device transmitting anadvertising event, that is, a device performing an advertisement and isalso termed an advertiser.

The scanning device refers to a device performing scanning, that is, adevice transmitting a scan request.

In the BLE, in a case in which the scanning device receives someadvertising packets from the advertising device, the scanning deviceshould transmit a scan request to the advertising device.

However, in a case in which a device filtering procedure is used so ascan request transmission is not required, the scanning device maydisregard the advertising packets transmitted from the advertisingdevice.

Even in a connection request process, the device filtering procedure maybe used. In a case in which device filtering is used in the connectionrequest process, it is not necessary to transmit a response with respectto the connection request by disregarding the connection request.

Advertising Procedure

The advertising device performs an advertising procedure to performundirected broadcast to devices within a region.

Here, the undirected broadcast is advertising toward all the devices,rather than broadcast toward a specific device, and all the devices mayscan advertising to make an supplemental information request or aconnection request.

In contrast, directed advertising may make an supplemental informationrequest or a connection request by scanning advertising for only adevice designated as a reception device.

The advertising procedure is used to establish a Bluetooth connectionwith an initiating device nearby.

Or, the advertising procedure may be used to provide periodicalbroadcast of user data to scanning devices performing listening in anadvertising channel.

In the advertising procedure, all the advertisements (or advertisingevents) are broadcast through an advertisement physical channel.

The advertising devices may receive scan requests from listening devicesperforming listening to obtain additional user data from advertisingdevices. The advertising devices transmit responses with respect to thescan requests to the devices which have transmitted the scan requests,through the same advertising physical channels as the advertisingphysical channels in which the scan requests have been received.

Broadcast user data sent as part of advertising packets are dynamicdata, while the scan response data is generally static data.

The advertisement device may receive a connection request from aninitiating device on an advertising (broadcast) physical channel. If theadvertising device has used a connectable advertising event and theinitiating device has not been filtered according to the devicefiltering procedure, the advertising device may stop advertising andenter a connected mode. The advertising device may start advertisingafter the connected mode.

Scanning Procedure

A device performing scanning, that is, a scanning device performs ascanning procedure to listen to undirected broadcasting of user datafrom advertising devices using an advertising physical channel.

The scanning device transmits a scan request to an advertising devicethrough an advertising physical channel in order to request additionaldata from the advertising device. The advertising device transmits ascan response as a response with respect to the scan request, byincluding additional user data which has requested by the scanningdevice through an advertising physical channel.

The scanning procedure may be used while being connected to other BLEdevice in the BLE piconet.

If the scanning device is in an initiator mode in which the scanningdevice may receive an advertising event and initiates a connectionrequest. The scanning device may transmit a connection request to theadvertising device through the advertising physical channel to start aBluetooth connection with the advertising device.

When the scanning device transmits a connection request to theadvertising device, the scanning device stops the initiator modescanning for additional broadcast and enters the connected mode.

Discovering Procedure

Devices available for Bluetooth communication (hereinafter, referred toas “Bluetooth devices”) perform an advertising procedure and a scanningprocedure in order to discover devices located nearby or in order to bediscovered by other devices within a given area.

The discovering procedure is performed asymmetrically. A Bluetoothdevice intending to discover other device nearby is termed a discoveringdevice, and listens to discover devices advertising an advertising eventthat may be scanned. A Bluetooth device which may be discovered by otherdevice and available to be used is termed a discoverable device andpositively broadcasts an advertising event such that it may be scannedby other device through an advertising (broadcast) physical channel.

Both the discovering device and the discoverable device may have alreadybeen connected with other Bluetooth devices in a piconet.

Connecting Procedure

A connecting procedure is asymmetrical, and requests that, while aspecific Bluetooth device is performing an advertising procedure,another Bluetooth device should perform a scanning procedure.

That is, an advertising procedure may be aimed, and as a result, onlyone device may response to the advertising. After a connectableadvertising event is received from an advertising device, a connectingrequest may be transmitted to the advertising device through anadvertising (broadcast) physical channel to initiate connection.

Hereinafter, operational states, that is, an advertising state, ascanning state, an initiating state, and a connection state, in the BLEtechnology will be briefly described.

Advertising State

A link layer (LL) enters an advertising state according to aninstruction from a host (stack). In a case in which the LL is in theadvertising state, the LL transmits an advertising packet data unit(PDU) in advertising events.

Each of the advertising events include at least one advertising PDU, andthe advertising PDU is transmitted through an advertising channel indexin use. After the advertising PDU is transmitted through an advertisingchannel index in use, the advertising event may be terminated, or in acase in which the advertising device may need to secure a space forperforming other function, the advertising event may be terminatedearlier.

Scanning State

The LL enters the scanning state according to an instruction from thehost (stack). In the scanning state, the LL listens to advertisingchannel indices.

The scanning state includes two types: passive scanning and activescanning. Each of the scanning types is determined by the host.

Time for performing scanning or an advertising channel index are notdefined.

During the scanning state, the LL listens to an advertising channelindex in a scan window duration. A scan interval is defined as aninterval between start points of two continuous scan windows.

When there is no collision in scheduling, the LL should listen in orderto complete all the scan intervals of the scan window as instructed bythe host. In each scan window, the LL should scan other advertisingchannel index. The LL uses every available advertising channel index.

In the passive scanning, the LL only receives packets and cannottransmit any packet.

In the active scanning, the LL performs listening in order to be reliedon an advertising PDU type for requesting advertising PDUs andadvertising device-related supplemental information from the advertisingdevice.

Initiating State

The LL enters the initiating state according to an instruction from thehost (stack).

When the LL is in the initiating state, the LL performs listening onadvertising channel indices.

During the initiating state, the LL listens to an advertising channelindex during the scan window interval.

Connection State

When the device performing a connection state, that is, when theinitiating device transmits a CONNECT_REQ PDU to the advertising deviceor when the advertising device receives a CONNECT_REQ PDU from theinitiating device, the LL enters a connection state.

It is considered that a connection is generated after the LL enters theconnection state. However, it is not necessary to consider that theconnection should be established at a point in time at which the LLenters the connection state. The only difference between a newlygenerated connection and an already established connection is a LLconnection supervision timeout value.

When two devices are connected, the two devices play different roles.

An LL serving as a master is termed a master, and an LL serving as aslave is termed a slave. The master adjusts a timing of a connectingevent, and the connecting event refers to a point in time at which themaster and the slave are synchronized.

Hereinafter, packets defined in an Bluetooth interface will be brieflydescribed. BLE devices use packets defined as follows.

Packet Format

The LL has only one packet format used for both an advertising channelpacket and a data channel packet.

Each packet includes four fields of a preamble, an access address, aPDU, and a CRC.

When one packet is transmitted in an advertising physical channel, thePDU may be an advertising channel PDU, and when one packet istransmitted in a data physical channel, the PDU may be a data channelPDU.

Advertising Channel PDU

An advertising channel PDU has a 16-bit header and payload havingvarious sizes.

A PDU type field of the advertising channel PDU included in the heaterindicates PDU types defined in Table 3 below.

TABLE 3 PDU Type Packet_Name 0000 ADV_IND 0001 ADV_DIRECT_IND 0010ADV_NONCONN_IND 0011 SCAN_REQ 0100 SCAN_RSP 0101 CONNECT_REQ 0110ADV_SCAN_IND 0111-1111 Reserved

Advertising PDU

The following advertising channel PDU types are termed advertising PDUsand used in a specific event.

ADV_IND: Connectable undirected advertising event

ADV_DIRECT_IND: Connectable directed advertising event

ADV_NONCONN_IND: Unconnectable undirected advertising event

ADV_SCAN_IND: Scannable undirected advertising event

The PDUs are transmitted from the LL in an advertising state, andreceived by the LL in a scanning state or in an initiating state.

Scanning PDU

The following advertising channel DPU types are termed scanning PDUs andare used in a state described hereinafter.

SCAN_REQ: Transmitted by the LL in a scanning state and received by theLL in an advertising state.

SCAN_RSP: Transmitted by the LL in the advertising state and received bythe LL in the scanning state.

Initiating PDU

The following advertising channel PDU type is termed an initiating PDU.

CONNECT_REQ: Transmitted by the LL in the initiating state and receivedby the LL in the advertising state.

Data Channel PDU

The data channel PDU may include a message integrity check (MIC) fieldhaving a 16-bit header and payload having various sizes.

The procedures, states, and packet formats in the BLE technologydiscussed above may be applied to perform the methods proposed in thepresent disclosure.

Referring to FIG. 4a , The load (455) may correspond to a battery. Thebattery may store energy by using the power that is being outputted fromthe power pick-up unit (210). Meanwhile, the battery is not mandatorilyrequired to be included in the mobile device (450). For example, thebattery may be provided as a detachable external feature. As anotherexample, the wireless power receiver may include an operating means thatmay execute diverse functions of the electronic device instead of thebattery.

As shown in the drawing, although the mobile device (450) is illustratedto be included in the wireless power receiver (200) and the base station(400) is illustrated to be included in the wireless power transmitter(100), in a broader meaning, the wireless power receiver (200) may beidentified (or regarded) as the mobile device (450), and the wirelesspower transmitter (100) may be identified (or regarded) as the basestation (400).

When the communication/control circuit 120 and the communication/controlcircuit 220 include Bluetooth or Bluetooth LE as an OB communicationmodule or a short-range communication module in addition to the IBcommunication module, the wireless power transmitter 100 including thecommunication/control circuit 120 and the wireless power receiver 200including the communication/control circuit 220 may be represented by asimplified block diagram as shown in FIG. 4C.

FIG. 4C is a block diagram illustrating a wireless power transfer systemusing BLE communication according to an example.

Referring to FIG. 4C, the wireless power transmitter 100 includes apower conversion circuit 110 and a communication/control circuit 120.The communication/control circuit 120 includes an in-band communicationmodule 121 and a BLE communication module 122.

Meanwhile, the wireless power receiver 200 includes a power pickupcircuit 210 and a communication/control circuit 220. Thecommunication/control circuit 220 includes an in-band communicationmodule 221 and a BLE communication module 222.

In one aspect, the BLE communication modules 122 and 222 perform thearchitecture and operation according to FIG. 4B. For example, the BLEcommunication modules 122 and 222 may be used to establish a connectionbetween the wireless power transmitter 100 and the wireless powerreceiver 200 and exchange control information and packets necessary forwireless power transfer.

In another aspect, the communication/control circuit 120 may beconfigured to operate a profile for wireless charging. Here, the profilefor wireless charging may be GATT using BLE transmission.

FIG. 4D is a block diagram illustrating a wireless power transfer systemusing BLE communication according to another example.

Referring to FIG. 4D, the communication/control circuits 120 and 220respectively include only in-band communication modules 121 and 221, andthe BLE communication modules 122 and 222 may be provided to beseparated from the communication/control circuits 120 and 220.

Hereinafter, the coil or coil unit includes a coil and at least onedevice being approximate to the coil, and the coil or coil unit may alsobe referred to as a coil assembly, a coil cell, or a cell.

FIG. 5 is a state transition diagram for describing a wireless powertransfer procedure.

Referring to FIG. 5, the power transfer (or transfer) from the wirelesspower transmitter to the wireless power receiver according to anexemplary embodiment of the present disclosure may be broadly dividedinto a selection phase (510), a ping phase (520), an identification andconfiguration phase (530), a negotiation phase (540), a calibrationphase (550), a power transfer phase (560), and a renegotiation phase(570).

If a specific error or a specific event is detected when the powertransfer is initiated or while maintaining the power transfer, theselection phase (510) may include a shifting phase (or step)—referencenumerals S502, S504, S508, S510, and S512. Herein, the specific error orspecific event will be specified in the following description.Additionally, during the selection phase (510), the wireless powertransmitter may monitor whether or not an object exists on an interfacesurface. If the wireless power transmitter detects that an object isplaced on the interface surface, the process step may be shifted to theping phase (520). During the selection phase (510), the wireless powertransmitter may transmit an analog ping having a power signal(or apulse) corresponding to an extremely short duration, and may detectwhether or not an object exists within an active area of the interfacesurface based on a current change in the transmitting coil or theprimary coil.

In case an object is sensed (or detected) in the selection phase (510),the wireless power transmitter may measure a quality factor of awireless power resonance circuit (e.g., power transfer coil and/orresonance capacitor). According to the exemplary embodiment of thepresent disclosure, during the selection phase (510), the wireless powertransmitter may measure the quality factor in order to determine whetheror not a foreign object exists in the charging area along with thewireless power receiver. In the coil that is provided in the wirelesspower transmitter, inductance and/or components of the series resistancemay be reduced due to a change in the environment, and, due to suchdecrease, a value of the quality factor may also be decreased. In orderto determine the presence or absence of a foreign object by using themeasured quality factor value, the wireless power transmitter mayreceive from the wireless power receiver a reference quality factorvalue, which is measured in advance in a state where no foreign objectis placed within the charging area. The wireless power transmitter maydetermine the presence or absence of a foreign object by comparing themeasured quality factor value with the reference quality factor value,which is received during the negotiation phase (540). However, in caseof a wireless power receiver having a low reference quality factorvalue—e.g., depending upon its type, purpose, characteristics, and soon, the wireless power receiver may have a low reference quality factorvalue—in case a foreign object exists, since the difference between thereference quality factor value and the measured quality factor value issmall (or insignificant), a problem may occur in that the presence ofthe foreign object cannot be easily determined. Accordingly, in thiscase, other determination factors should be further considered, or thepresent or absence of a foreign object should be determined by usinganother method.

According to another exemplary embodiment of the present disclosure, incase an object is sensed (or detected) in the selection phase (510), inorder to determine whether or not a foreign object exists in thecharging area along with the wireless power receiver, the wireless powertransmitter may measure the quality factor value within a specificfrequency area (e.g., operation frequency area). In the coil that isprovided in the wireless power transmitter, inductance and/or componentsof the series resistance may be reduced due to a change in theenvironment, and, due to such decrease, the resonance frequency of thecoil of the wireless power transmitter may be changed (or shifted). Morespecifically, a quality factor peak frequency that corresponds to afrequency in which a maximum quality factor value is measured within theoperation frequency band may be moved (or shifted).

In the ping phase (520), if the wireless power transmitter detects thepresence of an object, the transmitter activates (or Wakes up) areceiver and transmits a digital ping for identifying whether or not thedetected object corresponds to the wireless power receiver. During theping phase (520), if the wireless power transmitter fails to receive aresponse signal for the digital ping—e.g., a signal intensitypacket—from the receiver, the process may be shifted back to theselection phase (510). Additionally, in the ping phase (520), if thewireless power transmitter receives a signal indicating the completionof the power transfer—e.g., charging complete packet—from the receiver,the process may be shifted back to the selection phase (510).

If the ping phase (520) is completed, the wireless power transmitter mayshift to the identification and configuration phase (530) foridentifying the receiver and for collecting configuration and statusinformation.

In the identification and configuration phase (530), if the wirelesspower transmitter receives an unwanted packet (i.e., unexpected packet),or if the wireless power transmitter fails to receive a packet during apredetermined period of time (i.e., out of time), or if a packettransmission error occurs (i.e., transmission error), or if a powertransfer contract is not configured (i.e., no power transfer contract),the wireless power transmitter may shift to the selection phase (510).

The wireless power transmitter may confirm (or verify) whether or notits entry to the negotiation phase (540) is needed based on aNegotiation field value of the configuration packet, which is receivedduring the identification and configuration phase (530). Based on theverified result, in case a negotiation is needed, the wireless powertransmitter enters the negotiation phase (540) and may then perform apredetermined FOD detection procedure. Conversely, in case a negotiationis not needed, the wireless power transmitter may immediately enter thepower transfer phase (560).

In the negotiation phase (540), the wireless power transmitter mayreceive a Foreign Object Detection (FOD) status packet that includes areference quality factor value. Or, the wireless power transmitter mayreceive an FOD status packet that includes a reference peak frequencyvalue. Alternatively, the wireless power transmitter may receive astatus packet that includes a reference quality factor value and areference peak frequency value. At this point, the wireless powertransmitter may determine a quality coefficient threshold value for FOdetection based on the reference quality factor value. The wirelesspower transmitter may determine a peak frequency threshold value for FOdetection based on the reference peak frequency value.

The wireless power transmitter may detect the presence or absence of anFO in the charging area by using the determined quality coefficientthreshold value for FO detection and the currently measured qualityfactor value (i.e., the quality factor value that was measured beforethe ping phase), and, then, the wireless power transmitter may controlthe transmitted power in accordance with the FO detection result. Forexample, in case the FO is detected, the power transfer may be stopped.However, the present disclosure will not be limited only to this.

The wireless power transmitter may detect the presence or absence of anFO in the charging area by using the determined peak frequency thresholdvalue for FO detection and the currently measured peak frequency value(i.e., the peak frequency value that was measured before the pingphase), and, then, the wireless power transmitter may control thetransmitted power in accordance with the FO detection result. Forexample, in case the FO is detected, the power transfer may be stopped.However, the present disclosure will not be limited only to this.

In case the FO is detected, the wireless power transmitter may return tothe selection phase (510). Conversely, in case the FO is not detected,the wireless power transmitter may proceed to the calibration phase(550) and may, then, enter the power transfer phase (560). Morespecifically, in case the FO is not detected, the wireless powertransmitter may determine the intensity of the received power that isreceived by the receiving end during the calibration phase (550) and maymeasure power loss in the receiving end and the transmitting end inorder to determine the intensity of the power that is transmitted fromthe transmitting end. In other words, during the calibration phase(550), the wireless power transmitter may estimate the power loss basedon a difference between the transmitted power of the transmitting endand the received power of the receiving end. The wireless powertransmitter according to the exemplary embodiment of the presentdisclosure may calibrate the threshold value for the FOD detection byapplying the estimated power loss.

In the power transfer phase (560), in case the wireless powertransmitter receives an unwanted packet (i.e., unexpected packet), or incase the wireless power transmitter fails to receive a packet during apredetermined period of time (i.e., time-out), or in case a violation ofa predetermined power transfer contract occurs (i.e., power transfercontract violation), or in case charging is completed, the wirelesspower transmitter may shift to the selection phase (510).

Additionally, in the power transfer phase (560), in case the wirelesspower transmitter is required to reconfigure the power transfer contractin accordance with a status change in the wireless power transmitter,the wireless power transmitter may shift to the renegotiation phase(570). At this point, if the renegotiation is successfully completed,the wireless power transmitter may return to the power transfer phase(560).

In this embodiment, the calibration step 550 and the power transferphase 560 are divided into separate steps, but the calibration step 550may be integrated into the power transfer phase 560. In this case,operations in the calibration step 550 may be performed in the powertransfer phase 560.

The above-described power transfer contract may be configured based onthe status and characteristic information of the wireless powertransmitter and receiver. For example, the wireless power transmitterstatus information may include information on a maximum amount oftransmittable power, information on a maximum number of receivers thatmay be accommodated, and so on. And, the receiver status information mayinclude information on the required power, and so on.

FIG. 6 shows a power control method according to an exemplary embodimentof the present disclosure.

As shown in FIG. 6, in the power transfer phase (560), by alternatingthe power transfer and/or reception and communication, the wirelesspower transmitter (100) and the wireless power receiver (200) maycontrol the amount (or size) of the power that is being transferred. Thewireless power transmitter and the wireless power receiver operate at aspecific control point. The control point indicates a combination of thevoltage and the electric current that are provided from the output ofthe wireless power receiver, when the power transfer is performed.

More specifically, the wireless power receiver selects a desired controlpoint, a desired output current/voltage, a temperature at a specificlocation of the mobile device, and so on, and additionally determines anactual control point at which the receiver is currently operating. Thewireless power receiver calculates a control error value by using thedesired control point and the actual control point, and, then, thewireless power receiver may transmit the calculated control error valueto the wireless power transmitter as a control error packet.

Also, the wireless power transmitter may configure/control a newoperating point—amplitude, frequency, and duty cycle—by using thereceived control error packet, so as to control the power transfer.Therefore, the control error packet may be transmitted/received at aconstant time interval during the power transfer phase, and, accordingto the exemplary embodiment, in case the wireless power receiverattempts to reduce the electric current of the wireless powertransmitter, the wireless power receiver may transmit the control errorpacket by setting the control error value to a negative number. And, incase the wireless power receiver intends to increase the electriccurrent of the wireless power transmitter, the wireless power receivertransmit the control error packet by setting the control error value toa positive number. During the induction mode, by transmitting thecontrol error packet to the wireless power transmitter as describedabove, the wireless power receiver may control the power transfer.

In the resonance mode, which will hereinafter be described in detail,the device may be operated by using a method that is different from theinduction mode. In the resonance mode, one wireless power transmittershould be capable of serving a plurality of wireless power receivers atthe same time. However, in case of controlling the power transfer justas in the induction mode, since the power that is being transferred iscontrolled by a communication that is established with one wirelesspower receiver, it may be difficult to control the power transfer ofadditional wireless power receivers. Therefore, in the resonance modeaccording to the present disclosure, a method of controlling the amountof power that is being received by having the wireless power transmittercommonly transfer (or transmit) the basic power and by having thewireless power receiver control its own resonance frequency.Nevertheless, even during the operation of the resonance mode, themethod described above in FIG. 6 will not be completely excluded. And,additional control of the transmitted power may be performed by usingthe method of FIG. 6.

FIG. 7 is a block diagram of a wireless power transmitter according toanother exemplary embodiment of the present disclosure. This may belongto a wireless power transfer system that is being operated in themagnetic resonance mode or the shared mode. The shared mode may refer toa mode performing a several-for-one (or one-to-many) communication andcharging between the wireless power transmitter and the wireless powerreceiver. The shared mode may be implemented as a magnetic inductionmethod or a resonance method.

Referring to FIG. 7, the wireless power transmitter (700) may include atleast one of a cover (720) covering a coil assembly, a power adapter(730) supplying power to the power transmitter (740), a powertransmitter (740) transmitting wireless power, and a user interface(750) providing information related to power transfer processing andother related information. Most particularly, the user interface (750)may be optionally included or may be included as another user interface(750) of the wireless power transmitter (700).

The power transmitter (740) may include at least one of a coil assembly(760), an impedance matching circuit (770), an inverter (780), acommunication unit (790), and a control unit (710).

The coil assembly (760) includes at least one primary coil generating amagnetic field. And, the coil assembly (760) may also be referred to asa coil cell.

The impedance matching circuit (770) may provide impedance matchingbetween the inverter and the primary coil(s). The impedance matchingcircuit (770) may generate resonance from a suitable frequency thatboosts the electric current of the primary coil(s). In a multi-coilpower transmitter (740), the impedance matching circuit may additionallyinclude a multiplex that routes signals from the inverter to a subset ofthe primary coils. The impedance matching circuit may also be referredto as a tank circuit.

The impedance matching circuit (770) may include a capacitor, aninductor, and a switching device that switches the connection betweenthe capacitor and the inductor. The impedance matching may be performedby detecting a reflective wave of the wireless power that is beingtransferred (or transmitted) through the coil assembly (760) and byswitching the switching device based on the detected reflective wave,thereby adjusting the connection status of the capacitor or the inductoror adjusting the capacitance of the capacitor or adjusting theinductance of the inductor. In some cases, the impedance matching may becarried out even though the impedance matching circuit (770) is omitted.This specification also includes an exemplary embodiment of the wirelesspower transmitter (700), wherein the impedance matching circuit (770) isomitted.

The inverter (780) may convert a DC input to an AC signal. The inverter(780) may be operated as a half-bridge inverter or a full-bridgeinverter in order to generate a pulse wave and a duty cycle of anadjustable frequency. Additionally, the inverter may include a pluralityof stages in order to adjust input voltage levels.

The communication unit (790) may perform communication with the powerreceiver. The power receiver performs load modulation in order tocommunicate requests and information corresponding to the powertransmitter. Therefore, the power transmitter (740) may use thecommunication unit (790) so as to monitor the amplitude and/or phase ofthe electric current and/or voltage of the primary coil in order todemodulate the data being transmitted from the power receiver.

Additionally, the power transmitter (740) may control the output powerto that the data may be transferred through the communication unit (790)by using a Frequency Shift Keying (FSK) method, and so on.

The control unit (710) may control communication and power transfer (ordelivery) of the power transmitter (740). The control unit (710) maycontrol the power transfer by adjusting the above-described operatingpoint. The operating point may be determined by, for example, at leastany one of the operation frequency, the duty cycle, and the inputvoltage.

The communication unit (790) and the control unit (710) may each beprovided as a separate unit/device/chipset or may be collectivelyprovided as one unit/device/chipset.

FIG. 8 shows a wireless power receiver according to another exemplaryembodiment of the present disclosure. This may belong to a wirelesspower transfer system that is being operated in the magnetic resonancemode or the shared mode.

Referring to FIG. 8, the wireless power receiver (800) may include atleast one of a user interface (820) providing information related topower transfer processing and other related information, a powerreceiver (830) receiving wireless power, a load circuit (840), and abase (850) supporting and covering the coil assembly. Most particularly,the user interface (820) may be optionally included or may be includedas another user interface (820) of the wireless power receiver (800).

The power receiver (830) may include at least one of a power converter(860), an impedance matching circuit (870), a coil assembly (880), acommunication unit (890), and a control unit (810).

The power converter (860) may convert the AC power that is received fromthe secondary coil to a voltage and electric current that are suitablefor the load circuit. According to an exemplary embodiment, the powerconverter (860) may include a rectifier. The rectifier may rectify thereceived wireless power and may convert the power from an alternatingcurrent (AC) to a direct current (DC). The rectifier may convert thealternating current to the direct current by using a diode or atransistor, and, then, the rectifier may smooth the converted current byusing the capacitor and resistance. Herein, a full-wave rectifier, ahalf-wave rectifier, a voltage multiplier, and so on, that areimplemented as a bridge circuit may be used as the rectifier.Additionally, the power converter may adapt a reflected impedance of thepower receiver.

The impedance matching circuit (870) may provide impedance matchingbetween a combination of the power converter (860) and the load circuit(840) and the secondary coil. According to an exemplary embodiment, theimpedance matching circuit may generate a resonance of approximately 100kHz, which may reinforce the power transfer. The impedance matchingcircuit (870) may include a capacitor, an inductor, and a switchingdevice that switches the combination of the capacitor and the inductor.The impedance matching may be performed by controlling the switchingdevice of the circuit that configured the impedance matching circuit(870) based on the voltage value, electric current value, power value,frequency value, and so on, of the wireless power that is beingreceived. In some cases, the impedance matching may be carried out eventhough the impedance matching circuit (870) is omitted. Thisspecification also includes an exemplary embodiment of the wirelesspower receiver (200), wherein the impedance matching circuit (870) isomitted.

The coil assembly (880) includes at least one secondary coil, and,optionally, the coil assembly (880) may further include an elementshielding the metallic part of the receiver from the magnetic field.

The communication unit (890) may perform load modulation in order tocommunicate requests and other information to the power transmitter.

For this, the power receiver (830) may perform switching of theresistance or capacitor so as to change the reflected impedance.

The control unit (810) may control the received power. For this, thecontrol unit (810) may determine/calculate a difference between anactual operating point and a target operating point of the powerreceiver (830). Thereafter, by performing a request for adjusting thereflected impedance of the power transmitter and/or for adjusting anoperating point of the power transmitter, the difference between theactual operating point and the target operating point may beadjusted/reduced. In case of minimizing this difference, an optimalpower reception may be performed.

The communication unit (890) and the control unit (810) may each beprovided as a separate device/chipset or may be collectively provided asone device/chipset.

FIG. 9 shows a communication frame structure according to an exemplaryembodiment of the present disclosure. This may correspond to acommunication frame structure in a shared mode.

Referring to FIG. 9, in the shared mode, different forms of frames maybe used along with one another. For example, in the shared mode, aslotted frame having a plurality of slots, as shown in (A), and a freeformat frame that does not have a specified format, as shown in (B), maybe used. More specifically, the slotted frame corresponds to a frame fortransmitting short data packets from the wireless power receiver (200)to the wireless power transmitter (100). And, since the free formatframe is not configured of a plurality of slots, the free format framemay correspond to a frame that is capable of performing transmission oflong data packets.

Meanwhile, the slotted frame and the free format frame may be referredto other diverse terms by anyone skilled in the art. For example, theslotted frame may be alternatively referred to as a channel frame, andthe free format frame may be alternatively referred to as a messageframe.

More specifically, the slotted frame may include a sync patternindicating the starting point (or beginning) of a slot, a measurementslot, nine slots, and additional sync patterns each having the same timeinterval that precedes each of the nine slots.

Herein, the additional sync pattern corresponds to a sync pattern thatis different from the sync pattern that indicates the starting point ofthe above-described frame. More specifically, the additional syncpattern does not indicate the starting point of the frame but mayindicate information related to the neighboring (or adjacent) slots(i.e., two consecutive slots positioned on both sides of the syncpattern).

Among the nine slots, each sync pattern may be positioned between twoconsecutive slots. In this case, the sync pattern may provideinformation related to the two consecutive slots.

Additionally, the nine slots and the sync patterns being provided beforeeach of the nine slots may have the same time interval. For example, thenine slots may have a time interval of 50 ms. And, the nine syncpatterns may have a time length of 50 ms.

Meanwhile, the free format frame, as shown in (B) may not have aspecific format apart from the sync pattern indicating the startingpoint of the frame and the measurement slot. More specifically, the freeformat frame is configured to perform a function that is different fromthat of the slotted frame. For example, the free format frame may beused to perform a function of performing communication of long datapackets (e.g., additional owner information packets) between thewireless power transmitter and the wireless power receiver, or, in caseof a wireless power transmitter being configured of multiple coils, toperform a function of selecting any one of the coils.

Hereinafter, a sync pattern that is included in each frame will bedescribed in more detail with reference to the accompanying drawings.

FIG. 10 is a structure of a sync pattern according to an exemplaryembodiment of the present disclosure.

Referring to FIG. 10, the sync pattern may be configured of a preamble,a start bit, a response field, a type field, an info field, and a paritybit. In FIG. 10, the start bit is illustrated as ZERO.

More specifically, the preamble is configured of consecutive bits, andall of the bits may be set to 0. In other words, the preamble maycorrespond to bits for matching a time length of the sync pattern.

The number of bits configuring the preamble may be subordinate to theoperation frequency so that the length of the sync pattern may be mostapproximate to 50 ms but within a range that does not exceed 50 ms. Forexample, in case the operation frequency corresponds to 100 kHz, thesync pattern may be configured of two preamble bits, and, in case theoperation frequency corresponds to 105 kHz, the sync pattern may beconfigured of three preamble bits.

The start bit may correspond to a bit that follows the preamble, and thestart bit may indicate ZERO. The ZERO may correspond to a bit thatindicates a type of the sync pattern. Herein, the type of sync patternsmay include a frame sync including information that is related to aframe, and a slot sync including information of the slot. Morespecifically, the sync pattern may be positioned between consecutiveframes and may correspond to a frame sync that indicate a start of theframe, or the sync pattern may be positioned between consecutive slotsamong a plurality of slots configuring the frame and may correspond to async slot including information related to the consecutive slots.

For example, in case the ZERO is equal to 0, this may indicate that thecorresponding slot is a slot sync that is positioned in-between slots.And, in case the ZERO is equal to 1, this may indicate that thecorresponding sync pattern is a frame sync being located in-betweenframes.

A parity bit corresponds to a last bit of the sync pattern, and theparity bit may indicate information on a number of bits configuring thedata fields (i.e., the response field, the type field, and the infofield) that are included in the sync pattern. For example, in case thenumber of bits configuring the data fields of the sync patterncorresponds to an even number, the parity bit may be set to when, and,otherwise (i.e., in case the number of bits corresponds to an oddnumber), the parity bit may be set to 0.

The response field may include response information of the wirelesspower transmitter for its communication with the wireless power receiverwithin a slot prior to the sync pattern. For example, in case acommunication between the wireless power transmitter and the wirelesspower receiver is not detected, the response field may have a value of‘00’. Additionally, if a communication error is detected in thecommunication between the wireless power transmitter and the wirelesspower receiver, the response field may have a value of ‘01’. Thecommunication error corresponds to a case where two or more wirelesspower receivers attempt to access one slot, thereby causing collision tooccur between the two or more wireless power receivers.

Additionally, the response field may include information indicatingwhether or not the data packet has been accurately received from thewireless power receiver. More specifically, in case the wireless powertransmitter has denied the data packet, the response field may have avalue of “10” (10—not acknowledge (NAK)). And, in case the wirelesspower transmitter has confirmed the data packet, the response field mayhave a value of “11” (11—acknowledge (ACK)).

The type field may indicate the type of the sync pattern. Morespecifically, in case the sync pattern corresponds to a first syncpattern of the frame (i.e., as the first sync pattern, in case the syncpattern is positioned before the measurement slot), the type field mayhave a value of ‘1’, which indicates a frame sync.

Additionally, in a slotted frame, in case the sync pattern does notcorrespond to the first sync pattern of the frame, the type field mayhave a value of ‘0’, which indicates a slot sync.

Moreover, the information field may determine the meaning of its valuein accordance with the sync pattern type, which is indicated in the typefield. For example, in case the type field is equal to 1 (i.e., in casethe sync pattern type indicates a frame sync), the meaning of theinformation field may indicate the frame type. More specifically, theinformation field may indicate whether the current frame corresponds toa slotted frame or a free-format frame. For example, in case theinformation field is given a value of ‘00’, this indicates that thecurrent frame corresponds to a slotted frame. And, in case theinformation field is given a value of ‘01’, this indicates that thecurrent frame corresponds to a free-format frame.

Conversely, in case the type field is equal to 0 (i.e., in case the syncpattern type indicates a slot sync), the information field may indicatea state of a next slot, which is positioned after the sync pattern. Morespecifically, in case the next slot corresponds to a slot that isallocated (or assigned) to a specific wireless power receiver, theinformation field is given a value of ‘00’. In case the next slotcorresponds to a slot that is locked, so as to be temporarily used bythe specific wireless power receiver, the information field is given avalue of ‘01’. Alternatively, in case the next slot corresponds to aslot that may be freely used by a random wireless power receiver, theinformation field is given a value of ‘10’.

FIG. 11 shows operation statuses of a wireless power transmitter and awireless power receiver in a shared mode according to an exemplaryembodiment of the present disclosure.

Referring to FIG. 11, the wireless power receiver operating in theshared mode may be operated in any one of a selection phase (1100), anintroduction phase (1110), a configuration phase (1120), a negotiationphase (1130), and a power transfer phase (1140).

Firstly, the wireless power transmitter according to the exemplaryembodiment of the present disclosure may transmit a wireless powersignal in order to detect the wireless power receiver. Morespecifically, a process of detecting a wireless power receiver by usingthe wireless power signal may be referred to as an Analog ping.

Meanwhile, the wireless power receiver that has received the wirelesspower signal may enter the selection phase (1100). As described above,the wireless power receiver that has entered the selection phase (1100)may detect the presence or absence of an FSK signal within the wirelesspower signal.

In other words, the wireless power receiver may perform communication byusing any one of an exclusive mode and a shared mode in accordance withthe presence or absence of the FSK signal.

More specifically, in case the FSK signal is included in the wirelesspower signal, the wireless power receiver may operate in the sharedmode, and, otherwise, the wireless power receiver may operate in theexclusive mode.

In case the wireless power receiver operates in the shared mode, thewireless power receiver may enter the introduction phase (1110). In theintroduction phase (1110), the wireless power receiver may transmit acontrol information (CI) packet to the wireless power transmitter inorder to transmit the control information packet during theconfiguration phase, the negotiation phase, and the power transferphase. The control information packet may have a header and informationrelated to control. For example, in the control information packet, theheader may correspond to 0X53.

In the introduction phase (1110), the wireless power receiver performsan attempt to request a free slot for transmitting the controlinformation (CI) packet during the following configuration phase,negotiation phase, and power transfer phase. At this point, the wirelesspower receiver selects a free slot and transmits an initial CI packet.If the wireless power transmitter transmits an ACK as a response to thecorresponding CI packet, the wireless power receiver enters theconfiguration phase. If the wireless power transmitter transmits a NAKas a response to the corresponding CI packet, this indicates thatanother wireless power receiver is performing communication through theconfiguration and negotiation phase. In this case, the wireless powerreceiver re-attempts to perform a request for a free slot.

If the wireless power receiver receives an ACK as a response to the CIpacket, the wireless power receiver may determine the position of aprivate slot within the frame by counting the remaining sync slots up tothe initial frame sync. In all of the subsequent slot-based frames, thewireless power receiver transmits the CI packet through thecorresponding slot.

If the wireless power transmitter authorizes the entry of the wirelesspower receiver to the configuration phase, the wireless powertransmitter provides a locked slot series for the exclusive usage of thewireless power receiver. This may ensure the wireless power receiver toproceed to the configuration phase without any collision.

The wireless power receiver transmits sequences of data packets, such astwo identification data packets (IDHI and IDLO), by using the lockedslots. When this phase is completed, the wireless power receiver entersthe negotiation phase. During the negotiation state, the wireless powertransmitter continues to provide the locked slots for the exclusiveusage of the wireless power receiver. This may ensure the wireless powerreceiver to proceed to the negotiation phase without any collision.

The wireless power receiver transmits one or more negotiation datapackets by using the corresponding locked slot, and the transmittednegotiation data packet(s) may be mixed with the private data packets.Eventually, the corresponding sequence is ended (or completed) alongwith a specific request (SRQ) packet. When the corresponding sequence iscompleted, the wireless power receiver enters the power transfer phase,and the wireless power transmitter stops the provision of the lockedslots.

In the power transfer phase, the wireless power receiver performs thetransmission of a CI packet by using the allocated slots and thenreceives the power. The wireless power receiver may include a regulatorcircuit. The regulator circuit may be included in acommunication/control unit. The wireless power receiver mayself-regulate a reflected impedance of the wireless power receiverthrough the regulator circuit. In other words, the wireless powerreceiver may adjust the impedance that is being reflected for an amountof power that is requested by an external load. This may prevent anexcessive reception of power and overheating.

In the shared mode, (depending upon the operation mode) since thewireless power transmitter may not perform the adjustment of power as aresponse to the received CI packet, in this case, control may be neededin order to prevent an overvoltage state.

Hereinafter, authentication between a wireless power transmitter and awireless power receiver will be disclosed.

The wireless power transfer system using in-band communication may useUSB-C authentication. The authentication may include an authenticationof the wireless power transmitter that is performed by the wirelesspower receiver (i.e., PTx Authentication by PRx), and an authenticationof the wireless power receiver that is performed by the wireless powertransmitter (PRx Authentication by PTx).

FIG. 12 is a block diagram showing a wireless charging certificateformat according to an exemplary embodiment of the present disclosure.

Referring to FIG. 12, the wireless charging certificate format includesa Certificate Structure Version, a reserved field, PTx and leafindicators, a certificate type, a signature offset, a serial number, anissuer ID, a subject ID, a public key, and a signature.

The certificate type may, for example, by assigned with 3 bits, and thecertificate type may indicate that the corresponding certificate is anyone of a root certificate, an intermediate certificate, and a lastcertificate. And, the certificate type may also indicate that thecorresponding certificate is a certificate relating to a wireless powertransmitter or a wireless power receiver or all type.

For example, the certificate type is 3 bits and may indicate informationon a root certificate, manufacturer/secondary certificate, and productunit certificate (for the power transmitter). More specifically, acertificate type ‘001’b may indicate the root certificate, and ‘010’bmay indicate an intermediate certificate (manufacturer/secondaryCertificate), and ‘111’b may indicate a product unit certificate for thepower transmitter, which is a final certificate.

The wireless power transmitter may notify (or announce) whether or notit supports the authentication function to the wireless power receiverby using a capability packet (in case of an authentication of thewireless power transmitter by the wireless power receiver(authentication of PTx by PRx)). Meanwhile, the wireless power receivermay notify (or announce) whether or not it supports the authenticationfunction to the wireless power transmitter by using a capability packet(in case of an authentication of the wireless power receiver by thewireless power transmitter (authentication of PRx by PTx)). Hereinafter,a structure of indication information (a capability packet and aconfiguration packet) related to whether or not a device supports theauthentication function will be disclosed and described in detail.

FIG. 13 is a capability packet structure of a wireless power transmitteraccording to an exemplary embodiment of the present disclosure.

Referring to FIG. 13, a capability packet having a respective headervalue of 0X31 is assigned with 3 bytes. Herein, a first byte (B0)includes a power class and a guaranteed power value, a second byte (B1)includes a reserved field and a potential power field, and a third byte(B2) includes an Authentication Initiator (AI), an AuthenticationResponder (AR), a reserved field, a WPID, and a Not Res Sens field. Morespecifically, the Authentication Initiator (AI) is assigned with 1 bit.Herein, for example, if the value is equal to ‘1b’, this may indicatethat the corresponding wireless power transmitter may operate as theauthentication initiator. Additionally, the Authentication Responder(AR) is also assigned with 1 bit. Herein, for example, if the value isequal to ‘1b’, this may indicate that the corresponding wireless powertransmitter may operate as the authentication responder.

FIG. 14 is a configuration packet structure of a wireless power receiveraccording to an exemplary embodiment of the present disclosure.

Referring to FIG. 14, a capability packet having a respective headervalue of 0X51 is assigned with 5 bytes. Herein, a first byte (B0)includes a power class and a maximum power value, a second byte (B1)includes an AI, an AR, a reserved field, a third byte (B2) includes aProp, a reserved field, a ZERO field, and a Count field, a fourth value(B3) includes a Window size and a window offset, and a fifth byte (B4)includes a Neg field, a polarity field, a Depth field, an authenticationfield (Auth), and a reserved field. More specifically, theAuthentication Initiator (AI) is assigned with 1 bit. Herein, forexample, if the value is equal to ‘1b’, this may indicate that thecorresponding wireless power receiver may operate as the authenticationinitiator. Additionally, the Authentication Responder (AR) is alsoassigned with 1 bit. Herein, for example, if the value is equal to ‘1b’,this may indicate that the corresponding wireless power receiver mayoperate as the authentication responder.

A message that is used during the authentication procedure is referredto as an authentication message. The authentication message is used forcarrying information related to authentication. Herein, 2 differenttypes of authentication messages exist. One type corresponds to anauthentication request, and another type corresponds to anauthentication response. The authentication request is transmitted bythe authentication initiator, and the authentication response istransmitted by the authentication responder. Both the wireless powertransmitter and the wireless power receiver may be the authenticationinitiator or the authentication responder. For example, in case thewireless power transmitter is the authentication initiator, the wirelesspower receiver becomes the authentication responder. And, in case thewireless power receiver is the authentication initiator, the wirelesspower transmitter becomes the authentication responder.

An authentication request message includes a GET_DIGESTS (i.e., 4bytes), a GET_CERTIFICATE (i.e., 8 bytes), and a CHALLENGE (i.e., 36bytes).

An authentication response message includes a DIGESTS (i.e., 4+32bytes), a CERTIFICATE (i.e., 4+certificate chain (3×512 bytes)=1,540bytes), a CHALLENGE_AUTH (i.e., 168 bytes), and an ERROR (i.e., 4bytes).

An authentication message may be referred to as an authentication packetand may also be referred to as authentication data or authenticationcontrol information. Additionally, messages, such as GET_DIGEST,DIGESTS, and so on, may also be referred to as a GET_DIGEST packet, aDIGEST packet, and so on.

FIG. 15 shows an application-level data stream between a wireless powertransmitter and a receiver according to an example.

Referring to FIG. 15, a data stream may include an auxiliary datacontrol (ADC) data packet and/or an auxiliary data transport (ADT) datapacket.

The ADC data packet is used to open a data stream. The ADC data packetmay indicate the type of a message included in a stream and the numberof data bytes. Meanwhile, the ADT data packet is sequences of dataincluding an actual message. An ADC/end data packet is used to indicatethe end of the stream. For example, the maximum number of data bytes ina data transport stream may be limited to 2047.

ACK or NAC (NACK) is used to indicate whether the ADC data packet andthe ADT data packet are normally received. Control information necessaryfor wireless charging such as a control error packet (CE) or DSR may betransmitted between transmission timings of the ADC data packet and theADT data packet.

Using this data stream structure, authentication related information orother application level information may be transmitted and receivedbetween the wireless power transmitter and the wireless power receiver.

Hereinafter, a method of detecting a foreign object and calibratingpower will be described.

When a wireless power transmitter transmits wireless power to a wirelesspower receiver using a magnetic field, if a foreign object is presenttherearound, a part of magnetic field may be absorbed to the foreignobject. That is, a part of the wireless power transmitted from thewireless power transmitter is supplied to the foreign object and therest is supplied to the wireless power receiver. From the viewpoint ofthe efficiency of power transfer, loss of transmitted power occurs asmuch as power or energy absorbed by the foreign object. Thus, since acausal relationship may be established between the presence of theforeign object and power loss (Ross), the wireless power transmitter maydetect how much power loss occurs through the foreign object. Such aforeign object detection method may be referred to as a foreign objectdetection method based on power loss.

The power lost by the foreign object may be defined as a value obtainedby subtracting the power (P_(received)) actually received by thewireless power receiver from the power (P_(transmitted)) transmittedfrom the wireless power transmitter. From the standpoint of the wirelesspower transmitter, the wireless power transmitter knows the power(P_(transmitted)) transmitted by itself, and thus, the lost power may beobtained if only the power actually received by the wireless powerreceiver is known. To this end, the wireless power receiver may notifythe wireless power transmitter of the received power by transmitting areceived power packet (RPP) to the wireless power transmitter.

Meanwhile, the wireless power transmitter and the wireless powerreceiver include various circuit components therein and configuredevices independent of each other. However, since wireless power istransmitted by magnetic coupling therebetween, the wireless powertransmitter and the wireless power receiver constitute one wirelesspower transfer system. In addition, the amount of power (transmittedpower) transmitted by the wireless power transmitter and the amount ofpower (received power) received by the wireless power receiver areuniquely determined by the power transfer characteristics. As anexample, power transfer characteristics may be considered as a ratio orfunction of transmitted power and received power. Therefore, if thewireless power transmitter knows the power transfer characteristics inadvance, the wireless power transmitter may be able to predict how muchof the power transmitted by the wireless power transmitter will bereceived by the wireless power receiver. If actual received powerreported by the wireless power receiver is smaller than received powerpredicted based on the power transfer characteristics, it may beconsidered that power loss occurred in the power transfer process. Theforeign object detection method based on power loss may determine that aforeign object exists in the above case. As described above, power lossused for the determination of a foreign object is also determined basedon the power transfer characteristics, and therefore, power transfercharacteristics need to be properly recognized to increase reliabilityof foreign object detection.

The power transfer characteristic is dependent on an environment inwhich wireless power is transmitted or a unique characteristic of adevice transmitting wireless power. The wireless power transmitter andthe wireless power receiver may generally use power calibration at thestart of wireless power transfer to determine the power transfercharacteristics in a certain currently given wireless chargingenvironment. When the power transfer characteristics are identified orset by power calibration, foreign object detection is performedaccordingly.

The power transfer characteristics may also be dependent on a change inload or a degree of magnetic coupling. For example, when the wirelesspower receiver uses multiple load steps or variable load (or loadincrease) or when the degree of a change in magnetic coupling due to achange in position between the wireless power transmitter and thewireless power receiver, at least a part of the power transfercharacteristics may be changed. If at least a part of the power transfercharacteristic changes, at least a part of power calibration setaccording to the previous power transfer characteristic becomes invalid.In addition, power loss and foreign object detection according to the atleast part of the set power calibration are no longer valid. Therefore,it is necessary to additionally calibrate power for the changed powertransfer characteristics.

Power Calibration Due to Load Change (1)

FIG. 16 is a flowchart illustrating a method of performing powercalibration and foreign object detection according to an embodiment.

Referring to FIG. 16, the wireless power receiver receives and measurestransmitted power (hereinafter, referred to as first light loadtransmitted power; Ptr_light) from the wireless power transmitter in alight-load condition and transmits a first received power packet (RPP)indicating a received power value under the light load condition to thewireless power transmitter (S1400). The first received power packet mayhave, for example, the format of FIG. 17.

FIG. 17 is a format of a received power packet according to an example.

Referring to FIG. 17, the received power packet totaling 24 bits, forexample, may include a field indicating an estimated received powervalue (e.g., 8 bits) and a mode field (e.g., 3 bits). The mode fieldindicates how to interpret the received power value. Table 4 shows anexample of the mode field.

TABLE 4 Mode Indication contents ‘000’ Normal value; Response requested‘001’ Light-load calibration value; Response requested ‘010’Connected-load calibration value; Response requested ‘011’ reserved‘100’ Normal value; no response requested

Referring to Table 4, the mode field=‘000’ indicates that a receivedpower value is a general power value (which may be indicated as RP/0),and the mode field=‘001’ or ‘010’ may indicate that a received powerpacket is related to power calibration (which may be indicated as RP/1,RP/2, respectively). That is, the wireless power receiver may instructpower calibration by transmitting the received power packet with themode field=‘001’ or ‘010’ to the wireless power transmitter.Specifically, the mode field=‘001’ (i.e., RP/1), the received powerpacket refers to the first information for constructing a powercalibration curve and may indicate a power value (hereinafter, referredto as a light-load calibration value, Prec_light) received by thewireless power receiver. In addition, when the mode field=‘010’ (i.e.,RP/2), the received power packet refers to additional information forconstructing a power calibration curve and may indicate a power valuereceived by the wireless power receiver (hereinafter, referred to as aconnected-load calibration value, Prec_connected) when the wirelesspower receiver is generally in a connected-load condition. The lightload condition may refer to a condition in which a load (e.g., abattery) is not electrically connected to the wireless power receiver,and the connected-load condition may refer to a condition in which aload is connected to the wireless power receiver. Meanwhile, thewireless power transmitter may know that power calibration is stillongoing by receiving the received power packet with the mode field=‘001’or ‘010’ from the wireless power receiver. Referring back to FIG. 16,since the first received power packet indicates the received power value(i.e., the light load calibration value, Prec_light) measured under thelight load condition, the mode field of the first received powerpacket=‘001’ (i.e., RP/1). Therefore, step S1400 may further include astep in which the wireless power receiver sets the mode field to ‘001’(mode field=‘001’). When it is determined that the mode field=‘001’, thewireless power transmitter may identify that the received power valueindicated by the first received power packet is first information forconstructing the power calibration curve, and the first information forconstructing the power calibration curve may be a light load calibrationvalue (Prec_light). The wireless power transmitter may store the lightload calibration value Prec_light in a memory to perform powercalibration. Although not shown, the wireless power transmitter maytransmit ACK or NAK to the wireless power receiver in response to thefirst received power packet. In addition, the first received powerpacket may be continuously transmitted a plurality of times until an ACKresponse is received from the wireless power transmitter. In this case,the first received power packet which is continuously transmitted (i.e.,RP/1) may be treated as one received power packet (i.e., a single RP/1).

In one aspect, when receiving the RP/1, the wireless power transmittertransmits NAK until the wireless power receiver stably reaches acorresponding power level (while monitoring a CE value), and when thepower level is stabilized, the wireless power transmitter transmits ACKand takes the RP1 value at that time.

The wireless power receiver receives and measures a first connected-loadtransmitted power (Ptr_connected (1)) from the wireless powertransmitter under the first connected load condition, and then transmitsa second received power packet (i.e., RP/2) indicating the firstconnected-load calibration value (Prec_connected(1)) to the wirelesspower transmitter (S1405).

Step S1405 may further include a step in which the wireless powerreceiver sets the mode field to ‘010’ (mode field=‘010’). When the modefield=‘010’ is confirmed, the wireless power transmitter identifies thatthe received power value indicated by the second received power packetis the first connected-load calibration value (Prec_connected (1)). Thewireless power transmitter may store the first connected-loadcalibration value (Prec_connected (1)) in the memory to perform powercalibration.

Although not shown, the wireless power transmitter may transmit an ACKor NAK to the wireless power receiver in response to the second receivedpower packet RP/2. Also, the second received power packet RP/2 may betransmitted multiple times in succession. In this case, the secondreceived power packet RP/2 which is continuously transmitted may betreated as one received power packet (i.e., a single RP/2). Whenreceiving the RP/2, the wireless power transmitter transmits NAK untilthe wireless power receiver stably reaches the corresponding power level(while monitoring the CE value), and when the power level is stabilized,the wireless power transmitter transmits ACK and takes the RP2 value atthat time.

The light load transmitted power (Ptr_light), the light load calibrationvalue (Prec_light), the first connected-load transmitted power(Ptr_connected (1)), and the first connected-load calibration value(Prec_connected (1)) obtained in steps S1400 and S1405 are called powercalibration data. Power transfer characteristics may be derived or setby the power calibration data. The derived power transfer characteristicmay be referred to as a calibration curve. Throughout thisspecification, the operation of calculating or deriving or setting thepower transfer characteristic or the operation of deriving or setting orcalculating the calibration curve is widely referred to as powercalibration. In this embodiment, the power calibration performed at thestart of the power transfer phase is called initial power calibration.Therefore, the wireless power transmitter performs initial powercalibration using RP1 and RP2 at the time of sending the ACK.

FIG. 18 is a power transfer characteristic or calibration curveaccording to an embodiment.

Referring to FIG. 18, when the power calibration data (light loadtransmitted power (Ptr_light), the light load calibration value(Prec_light), the first connected-load transmitted power (Ptr_connected(1)), and the first connected-load calibration value are expressed inthe form of coordinates (x, y) composed of a pair of transmission powerand reception power, one is first coordinates (Ptr_light, Prec_light)under the light load condition and the other is second coordinates(Ptr_connected (1), Prec_connected (1)) under the first connected-loadcondition.

If the graph is represented by linear interpolation based on the firstand second coordinates, a power transfer characteristic or a calibrationcurve as shown in FIG. 18 may be derived. The power transfercharacteristic (or calibration curve) is gradient a and a y-axis offsetis set by b. Here, a is a first calibration constant and b may be calleda second calibration constant.

The process of deriving the calibration constants a and b is expressedas follows

$\begin{matrix}{a = \frac{P_{received}^{({connected})} - P_{received}^{({light})}}{P_{transmitted}^{({connected})} - P_{transmitted}^{({light})}}} & \lbrack {{Equation}\mspace{14mu} 1} \rbrack \\{b = \frac{{P_{transmitted}^{({connected})}P_{received}^{({light})}} - {P_{received}^{({connected})}P_{transmitted}^{({light})}}}{P_{transmitted}^{({connected})} - P_{transmitted}^{({light})}}} & \lbrack {{Equation}\mspace{14mu} 2} \rbrack\end{matrix}$

Since the power transfer characteristic (or calibration curve) accordingto

FIG. 18 is derived using two coordinates according to two loadconditions, it may also be referred to as 2 point calibration.

Meanwhile, power calibration is valid within a range of the powercalibration data (i.e., the range in which the transmitted power Ptr isPtr_light≤Ptr≤Ptr_connected (1)). That is, when the first connected-loadtransmitted power is used as the power calibration data for powercalibration, the corresponding power calibration may be valid within arange less than or equal to the first connected-load transmitted power,and a range greater than the first connected-load transmitted power(e.g., a range of Ptr_connected (1)<Ptr) may not be valid. When thewireless power transmitter performs power calibration by extrapolating arange not covered by the calibration curve, false detection ornon-detection of a foreign object may be caused.

Referring back to FIG. 16, the wireless power receiver changes theconnected-load (S1410). The change in the connected-load may include anincrease or decrease in the connected-load. The change in theconnected-load may mean that a target rectified voltage (target Vrec) ortarget power of the wireless power receiver increases or decreasescompared to the previous connected-load. A situation in which theconnected-load is changed may include a case in which the wireless powerreceiver uses multiple load steps to reach the target power. When theconnected-load is changed, at least a part of the previously set powertransfer characteristics may be changed, or additional power transfercharacteristics may be set, while maintaining the previously set powertransfer characteristics. For example, if the transmitted power Ptrincreases to a range where Ptr_connected (1)<Ptr due to an increase inthe connected-load, the power transfer characteristic of FIG. 18 cannotcover this situation.

Therefore, additional power calibration data is required to reflect thechanged state of the connected-load in the power calibration. To thisend, the wireless power receiver receives and measures the secondconnected-load transmitted power (Ptr_connected (2)) from the wirelesspower transmitter under the second connected-load condition, and thentransmits a third received power packet indicating the secondconnected-load calibration value (Prec_connected (2)) to the wirelesspower transmitter (S1415). When the wireless power transmitter respondswith ACK to the second received power packet RP/2 in step S1410,additional RP/2 transmission of the wireless power receiver may not bepermitted. However, in order to improve the power loss-based foreignobject detection function, the limitation on the timing of powercalibration may be removed and multi-point power calibration of two ormore points may be required, and thus, the transmission of the thirdreceived power packet as in step S1415 may be permitted.

Step S1415 may further include a step in which the wireless powerreceiver set the mode field to ‘010’ (mode field=‘010’). When it isconfirmed that the mode field=‘010’, the wireless power transmitteridentifies that the received power value indicated by the third receivedpower packet is the second connected-load calibration value(Prec_connected (2)). Since the mode field=‘010’, the wireless powertransmitter may know that additional power calibration is required.

In order to perform power calibration, the wireless power transmittermay store the second connected-load calibration value (Prec_connected(2)) in a memory.

Power transfer characteristics may be derived or set based on the powercalibration data obtained in steps S1400 to S1415. FIG. 19 shows a graphrepresenting the derived power transfer characteristics by aninterpolation technique.

FIG. 19 is a power transfer characteristic or calibration curveaccording to another embodiment.

Referring to FIG. 19, when the power calibration data (light loadtransmitted power (Ptr_light), the light load calibration value(Prec_light), the first connected-load transmitted power (Ptr_connected(1)), the first connected-load calibration value (Prec_connected (1)),the second connected-load transmitted power (Ptr_connected (2)), and thesecond connected-load calibration value (Prec_connected (2)) arerepresented in the form of coordinates (x, y) consisting of a pair oftransmitted power and received power, first coordinates (Ptr_light,Prec_light), second coordinates (Ptr_connected (1), Prec_connected (1)),and third coordinates (Ptr_connected (2), Prec_connected (2)) may beobtained.

When graphed by linear interpolation based on the first to thirdcoordinates, power transfer characteristics or calibration curves havingdifferent gradients for each section may be derived as illustrated inFIG. 19. For convenience of description, it is assumed that the first tothird coordinates are (x0, y0), (x1, y1), and (x2, y2), respectively.

The power transfer characteristic (or calibration curve) in a firstsection (x0 to x1) has a gradient a0 and a y-axis offset is derived byb0. In addition, the power transfer characteristic (or calibrationcurve) in a second section (x1 to x2) has a gradient a1 and a y-axisoffset is derived by b1. The process of deriving the calibrationconstants a0, b0, a1, and b1 is expressed as follows.

$\begin{matrix}{{a0} = \frac{{y\; 1} - {y\; 0}}{{x1} - {x\; 0}}} & \lbrack {{Equation}\mspace{14mu} 3} \rbrack \\{{b\; 0} = \frac{{y\; 0x\; 1} - {y\; 1x\; 0}}{{x1} - {x0}}} & \lbrack {{Equation}\mspace{14mu} 4} \rbrack \\{{a\; 1} = \frac{{y2} - {y1}}{{x2} - {x1}}} & \lbrack {{Equation}\mspace{14mu} 5} \rbrack \\{{b\; 1} = \frac{{y\; 1x\; 2} - {y\; 2x\; 1}}{{x2} - {x1}}} & \lbrack {{Equation}\mspace{14mu} 6} \rbrack\end{matrix}$

Since the power transfer characteristic (or calibration curve) accordingto FIG. 19 is derived using three coordinates based on the three loadconditions, it may also be referred to as 3 point calibration ormultiple calibration.

When comparing FIG. 19 and FIG. 18, it may be seen that the range ofcalibration of the 3 point calibration is increased to Ptr_connected (2)compared to a 2 point calibration. Therefore, it is possible to detect aforeign object even in a section in which the transmitted power isPtr_connected (2)<Ptr≤Ptr_connected (2).

Thereafter, when the wireless power receiver receives a received powerpacket indicating a normal value (i.e., mode field=‘000’b) P_(received),rather than the received power packet (i.e., mode field=‘001’b or‘010b’) related to power calibration no longer for the powerP_(transmitted) transmitted by the wireless power transmitter (S1420),the wireless power transmitter terminates the power calibration andperforms FOD based on the transmitted power P_(transmitted) and thereceived power P_(received) (S1425). For example, step S1425 may includea step in which the wireless power transmitter performs FOD based on thepower loss according to FIG. 20.

Although not shown in the figure, the wireless power transmittertransmits ACK or NAK to the wireless power receiver in response toreceiving of the received power packet related to power calibration.

Specifically, the wireless power transmitter may repeat the operation oftransmitting NAK to the wireless power receiver until control isachieved at a target operating point.

For example, according to the embodiment according to FIG. 16, after thewireless power receiver transmits the first received power packet to thewireless power transmitter (S1400), when the NAK is received, thewireless power receiver may transmit a control error packet to thewireless power transmitter, while changing operating points. Whencontrol is achieved to a target operating point, the wireless powertransmitter may transmit ACK to the wireless power receiver. From thestandpoint of the wireless power transmitter, the wireless powertransmitter determines whether the first received power packet istransmitted in a stable state of the wireless power receiver based onthe received control error packet. That is, when it is determined thatthe wireless power receiver is not stabilized, the wireless powertransmitter transmits NAK for the first received power packet, and whencontrol is achieved to a target operating point by changing operatingpoints, the wireless power transmitter transmits ACK to the wirelesspower receiver.

When the ACK is received in response to the first received power packet,the wireless power receiver transmits a second received power packet tothe wireless power transmitter (S1405). By transmitting a control errorpacket between the received power packets to the wireless powertransmitter, the wireless power receiver may inform the wireless powertransmitter about the degree to which the operating point of thewireless power receiver deviates from a target operating point. Thisoperation is repeated each time the wireless power receiver receives theNAK in response to the second received power packet, and is finallyterminated when the wireless power transmitter transmits ACK to thewireless power receiver when the wireless power transmitter iscontrolled to the target operating point.

Thereafter, due to a change in the connected-load (S1410), the wirelesspower receiver may transmit a third received power packet to thewireless power transmitter (S1415), and transmit a control error packetto the wireless power transmitter. This operation is repeated each timethe wireless power receiver receives the NAK in response to the secondreceived power packet, and then when the wireless power transmitter iscontrolled to the target operating point and transmits the ACK to thewireless power receiver, the wireless power transmitter terminates powercalibration.

Thereafter, when the wireless power receiver receives a received powerpacket indicating a normal value (i.e., mode field=‘000’b) Preceived,rather than the received power packet (i.e., mode field=‘001’b or‘010b’) related to power calibration no longer (S1420), the wirelesspower transmitter calibrates Preceived based on power calibration,calculates power loss, and performs FOD based on the power loss (S1425).

Meanwhile, another embodiment includes a wireless power transmitter andmethod and a wireless power receiver and method for performing powercalibration associated with an authentication procedure.

As an example, the wireless power receiver supporting authentication mayadaptively perform power calibration according to whether the wirelesspower transmitter is authenticated or by authentication performingsteps.

For example, the present embodiment includes a wireless power receiverand method including a step of performing power calibration using aconnected load corresponding to a basic power profile (BPP or 5V) at thetime of entering an initial power transfer phase, a step of verifyingthat the wireless power transmitter supports an authenticated (i.e.,Qi-certified) extended power profile (EPP or 5 W or greater), a step ofmaking a contract for power transfer with a desired target power value(i.e., 8 W or 15 W) when authentication is successfully performed as aresult of verification, and a step of transmitting a received powerpacket regarding power calibration to the wireless power transmitterunder a connected-load condition.

Thus, the wireless power transmitter is controlled to perform additionalpower calibration. Here, the step of making the contract for powertransfer with the target power value (i.e. 8 W or 15 W) may be performedin a renegotiation phase. When receiving the received power packet RP/1under the light load condition or the received power packet RP/2 underthe connected-load condition, the wireless power transmitter may informthe wireless power received that the power calibration operation hasbeen normally performed by sending an ACK signal for the RP(1) or RP(2)when it is controlled to the target operating point with reference to acontrol error packet value.

FIG. 20 is a flowchart illustrating a foreign object detection methodaccording to an embodiment.

Referring to FIG. 20, the wireless power transmitter compares transmitpower P_(transmitted) with power calibration data x0, x1, and x2 todetermine which calibration section the transmit power belongs to(S1800, S1820). If the transmit power P_(transmitted) exists between x0and x1 (S1800), the wireless power transmitter calculates a calibratedtransmit power value P_(calibrated) using the calibration constants a0and b0 (S1805). If the transmit power P_(transmitted) exists between x1and x2 (S1820), the wireless power transmitter calculates the calibratedtransmit power value P_(calibrated) using the calibration constants a1and b1 (S1825).

When the calibrated transmit power value P_(transmitted) is calculated,the wireless power transmitter calculates power loss P_(loss) from adifference between the calibrated transmit power value P_(transmitted)and the received power P_(received) (S1810). In addition, the wirelesspower transmitter detects a foreign object based on the power lossP_(loss) (S1815).

Since the calibration range is increased, a wider range of power valuesmay be calibrated, and since reliability of the calibration isincreased, the reliability of foreign object detection based on powerloss may also be increased.

This embodiment describes a case in which three received power packetsrelated to power calibration are continuously transmitted and received,but the present disclosure is not limited to the above embodiment. Thatis, the embodiment of the present disclosure may also include a casewhere more received power packets related to power calibration (e.g.,received power packets RP/1 and RP/ for power calibration calculation)are continuously transmitted and received according to the number ofchanging connected loads or the number of multiple load steps.

In addition, the present embodiment includes an operation of performingpower calibration during the power transfer phase if the load of thewireless power receiver changes in the power transfer phase. That is, insteps S1400 to S1425, the wireless power transmitter and the wirelesspower receiver are operating in the power transfer phase and thewireless power transmitter may continuously transmit wireless power.

The wireless power transmitter in the embodiments according to FIGS. 16to 20 corresponds to the wireless power transmission device, thewireless power transmitter, or power transmission part disclosed inFIGS. 1 to 15. Accordingly, the operation of the wireless powertransmitter in this embodiment is implemented by one or a combination oftwo or more of the components of the wireless power transmitter in FIGS.1 to 15. For example, in this embodiment, the operation of transmittingwireless power may be performed by the power conversion unit 110. Inaddition, in the present embodiment, the operation of receiving thereceived power packet, the operation of performing power calibration,the operation of deriving or calculating the power transfercharacteristic, the operation of performing FOD, etc., may be performedby the communication/control unit 120.

In addition, the wireless power receiver in the embodiment according toFIGS. 16 to 20 corresponds to the wireless power reception device, thewireless power receiver, or the power reception part disclosed in FIGS.1 to 15. Accordingly, the operation of the wireless power receiver inthis embodiment is implemented by one or a combination of two or more ofthe components of the wireless power receiver in FIGS. 1 to 15. Forexample, in this embodiment, an operation of receiving wireless powermay be performed by the power pickup unit 210. In addition, in thisembodiment, the operation of generating and transmitting the receivedpower packet, the operation of performing power calibration, theoperation of performing FOD, etc., may be performed by thecommunication/control unit 220.

FIG. 21 is a flowchart illustrating a method of performing powercalibration and foreign object detection according to anotherembodiment. This embodiment relates to power re-calibration thatperforms power calibration again after the renegotiation phase.

Referring to FIG. 21, the wireless power transmitter and the wirelesspower receiver in the negotiation step establish an initial basic powercontract (e.g., 5 W), and when the power transfer phase starts, thewireless power transmitter and the wireless power receiver perform powercalibration (S1900). Here, the power calibration may include powercalibration according to the embodiments described in FIGS. 16 to 20.

In one aspect, the power calibration according to step S1900 includes astep in which the wireless power receiver transmits a plurality ofreceived power packets related to power calibration to the wirelesspower transmitter and a step in which the wireless power transmitterperforms multiple calibrations using the power calibration dataaccording to the plurality of received power packets. As an example,when the plurality of received power packets is two received powerpackets, multiple calibration may be two-point calibration. In the caseof two-point calibration, a calibration curve or power transfercharacteristic derived according to step S1900 may be as shown in FIG.18. As another example, when the plurality of received power packets isthree received power packets, multiple calibration may be three pointcalibration. In the case of three-point calibration, a calibration curveor power transfer characteristic derived according to step S1900 may beas shown in FIG. 19.

The wireless power receiver transmits the first received power packetwith the mode field set to ‘000’b or ‘100’b (normal value) to thewireless power transmitter (S1905). The wireless power transmitterperforms FOD based on the first received power packet to check whetherthere is a foreign object (S1910), and if no foreign object is detected,the wireless power transmitter transmits an ACK response for the firstreceived power packet to the wireless power receiver (S1915). If it isdetermined that there is no foreign object based on the ACK response,the wireless power receiver transmits a renegotiation packet to thewireless power transmitter (S1920). In one aspect, the wireless powerreceiver supporting authentication may perform verification on thewireless power transmitter supporting authentication to determinewhether the wireless power transmitter has been authenticated, andrequest renegotiation if the wireless power transmitted has beenauthenticated. By transmitting a renegotiation packet, the wirelesspower receiver requests renegotiation to update an existing powercontract (e.g., increase to higher power). Here, the power contract maybe updated with a higher required power (GP) (i.e., greater than 5 W)than the existing power.

After the renegotiation phase, the wireless power receiver transmits thesecond received power packet with the mode field set to ‘010’b to thewireless power transmitter (S1925). That is, the second received powerpacket is related to power adjustment, and upon receiving the secondreceived power packet, the wireless power transmitter may perform poweradjustment again under the requested power (or target power) updated byrenegotiation.

When confirming that the mode field=‘010’, the wireless powertransmitter may store the received power value indicated by the secondreceived power packet in the memory and perform power calibration.Through power calibration, a power transfer characteristic (or acalibration curve) as shown in FIG. 19 may be derived, for example. Thatis, when power calibration data (light load transmitted power(Ptr_light), light load calibration value (Prec_light), firstconnected-load transmitted power (Ptr_connected (1)), firstconnected-load calibration value (Prec_connected (1)), secondconnected-load transmitted power (Ptr_connected (2)), and secondconnected-load calibration value (Prec_connected (2)) are represented inthe form of coordinates (x, y) composed of a pair of transmitted powerand reception power by power calibration, first coordinates (Ptr_light,Prec_light), second coordinates (Ptr_connected(1), Prec_connected(1)),and third coordinates (Ptr_connected(2), Prec_connected(2)) may bederived and power transfer characteristics or calibration curvesdifferent in gradient in each section may be derived as shown in FIG.19.

Meanwhile, steps S1920 and S1925 may be repeatedly performed.

Thereafter, when the wireless power receiver receives a received powerpacket indicating a normal value (i.e., mode field=‘000’b), rather thana received power packet (i.e., mode field=‘001’b or ‘010b’) related topower calibration no longer for the power P_(transmitted) transmitted bythe wireless power transmitter (S1930), the wireless power transmitterperforms FOD based on the transmitted power P_(transmitted) and thereceived power P_(received) (S1935). For example, step S1935 may includea step in which the wireless power transmitter performs FOD based onpower loss according to FIG. 20.

Meanwhile, another embodiment includes a wireless power transmitter andmethod and a wireless power receiver and method for performing powercalibration associated with an authentication procedure.

As an example, the wireless power receiver supporting authentication mayadaptively perform power calibration according to whether the wirelesspower transmitter is authenticated or by authentication performingsteps.

For example, the present embodiment includes a wireless power receiverand method including a step of performing power calibration using aconnected load corresponding to a basic power profile (BPP or 5V) at thetime of entering an initial power transfer phase, a step of verifyingthat the wireless power transmitter supports an authenticated (i.e.,Qi-certified) extended power profile (EPP or 5 W or greater), a step ofmaking a contract for power transfer with a desired target power value(i.e., 8 W or 15 W) when authentication is successfully performed as aresult of verification, and a step of transmitting a received powerpacket regarding power calibration to the wireless power transmitterunder a connected-load condition.

Thus, the wireless power transmitter is controlled to perform additionalpower calibration. Here, the step of making the contract for powertransfer with the target power value (i.e. 8 W or 15 W) may be performedin a renegotiation phase. When receiving the received power packet RP/1under the light load condition or the received power packet RP/2 underthe connected-load condition, the wireless power transmitter may informthe wireless power received that the power calibration operation hasbeen normally performed by sending an ACK signal for the RP(1) or RP(2)when it is controlled to the target operating point with reference to acontrol error packet value.

The wireless power transmitter in the embodiments according to FIG. 21corresponds to the wireless power transmission device, the wirelesspower transmitter, or power transmission part disclosed in FIGS. 1 to15. Accordingly, the operation of the wireless power transmitter in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power transmitter in FIGS. 1 to 15. Forexample, in this embodiment, the operation of transmitting wirelesspower may be performed by the power conversion unit 110. In addition, inthe present embodiment, the operation of receiving the received powerpacket, the operation of performing power calibration, the operation ofderiving or calculating the power transfer characteristic, the operationof performing FOD, etc., may be performed by the communication/controlunit 120.

In addition, the wireless power receiver in the embodiment according toFIG. 21 corresponds to the wireless power reception device, the wirelesspower receiver, or the power reception part disclosed in FIGS. 1 to 15.Accordingly, the operation of the wireless power receiver in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power receiver in FIGS. 1 to 15. For example,in this embodiment, an operation of receiving wireless power may beperformed by the power pickup unit 210. In addition, in this embodiment,the operation of generating and transmitting the received power packet,the operation of performing power calibration, the operation ofperforming FOD, etc., may be performed by the communication/control unit220.

As described above, the wireless power transmitter and the wirelesspower receiver perform initial power calibration using RP/1 and RP/2when entering the power transfer phase. Thereafter, when the wirelesspower receiver increases load power to RP/2 or greater, additional powercalibration may be performed. However, the wireless power receiver maytransmit an RP/2 packet for additional power calibration to the wirelesspower transmitter when the wireless power transmitter supports anadditional power calibration mode (e.g., WPC ver.1.3 or higher). Here,whether additional power calibration is supported by the wireless powertransmitter may be confirmed by a version number of a standard supportedby the wireless power transmitter. For example, the WPC Qi wirelesspower transmitter may support additional power calibration only inver.1.3 or higher. Meanwhile, regarding a wireless power transmittersupporting a higher version (e.g., WPC ver.1.3 or higher), the wirelesspower receiver may indicate RP/3 as shown in Table 5 and transmit thesame to distinguish the RP/2 packet for additional power calibrationfrom the existing RP/2.

Power Calibration Due to Change in Coupling and/or Foreign ObjectInsertion (1)

A position of the wireless power receiver may be changed by the user'sintention or may be changed regardless of the user's intention. Inaddition, the change in the position of the wireless power receivercauses a change in coupling between the wireless power transmitter andthe wireless power receiver. For example, if received power does notincrease despite increased transmitted power, it may be due to a changein coupling or foreign object insertion. Alternatively, after a controlerror (CE) converges to 0, if the CE is suddenly changed despite nointentional change to a load of the wireless power receiver, it may bedue to a change in coupling or foreign object insertion. The wirelesspower transmitter cannot discriminate between foreign object insertionand a change in coupling in the power transfer phase. When the wirelesspower transmitter detects a phenomenon related to a change in couplingor foreign object insertion, the wireless power transmitter may restartthe entire foreign object detection procedure from the beginning.

When the coupling is changed, the existing power calibration is nolonger valid because the power transfer characteristics at the lightload/connected load depend on a specific coupling condition. In otherwords, the power transfer characteristic derived under a specificcoupling condition is no longer valid if the coupling condition ischanged.

Hereinafter, a method of detecting a change in coupling and/or foreignobject insertion and a method of re-performing FOD and/or performingpower calibration according to a change in coupling and/or foreignobject insertion will be described in more detail. Hereinafter, forconvenience of description, the change in coupling and/or the insertionof a foreign object will be collectively referred to as a change incoupling. FIG. 22 is a flowchart illustrating an operation of thewireless power transmitter and the wireless power receiver according tothe present embodiment.

FIG. 22 is a flowchart illustrating an operation of a wireless powertransmitter and a wireless power receiver based on a change in couplingaccording to an embodiment.

Referring to FIG. 22, the wireless power transmitter transmits wirelesspower to the wireless power receiver in a power transfer phase (S2000).In the power transfer phase, the wireless power receiver transmits areceived power packet (RPP) and a control error packet (CEP) to thewireless power transmitter (S2005).

The wireless power transmitter monitors information on power transmittedin the power transfer phase and/or information (or packet) received fromthe wireless power receiver and detects the occurrence of a change incoupling based on the monitoring result (S2010).

As an example, if transmitted power (P_(transmitted)) increases eventhough there is no increase in received power, the wireless powertransmitter may determine that a change in coupling event has occurredor that a foreign object has been inserted.

As another example, after the control error (CE) converges to almost 0,if the CE is rapidly changed despite no intentional load change in thewireless power receiver while receiving RP/0, the wireless powertransmitter may determine that a coupling change event has occurred orthat a foreign object has been inserted. Here, the wireless powertransmitter may determine whether the change in the CE is due to anintentional change in the load condition of the wireless power receiverthrough the mode field of the received power packet (RPP). That is, thewireless power transmitter may determine whether a coupling change eventoccurs based on CEP and RPP.

When the change in coupling (or foreign object insertion) is detected instep S2010, the wireless power transmitter performs the entire FODprocedure again (Q factor-based FOD and APLD) to detect a foreign objector perform power calibration. Here, the power calibration includes anoperation of updating power calibration set before the change incoupling.

The wireless power transmitter may perform an operation of transmittinga specific bit pattern response to the wireless power receiver inresponse to the received power packet received in step S2005 in order toinform the wireless power receiver that a change in coupling hasoccurred (S2015).

FSK modulation may be used for transmission of the bit pattern response.For example, the bit pattern response is 8 bits and may be called ATN(attention) or RFC (request for communication). By setting the bitpattern response to a specific bit value and transmitting the same tothe wireless power receiver, the wireless power transmitter may requestthe wireless power receiver to transmit a DSR (Poll) packet, request thewireless power receiver to transmit a power-related packet, draw thewireless power receiver's attention, request the wireless power receiverto transmit a specific packet (e.g., EPT packet), or provide a responsefor a packet received from the wireless power receiver. Here, thepower-related packet may be an EPT packet or a re-ping initiationpacket. When the power-related packet is the EPT packet, the EPT packetmay include EPT/rst (0x0B).

As an example, an ACK response indicating a request approval may beindicated by a bit pattern of ‘11111111’, a NAK response rejecting arequest may be indicated by a bit pattern of ‘00000000’, and an NDresponse indicating an unrecognizable or invalid request may beindicated by a bit pattern of ‘01010101’. In addition, ATN may bedefined by various 8-bit sized bit patterns except for the bit patternsdefined for the above ACK/NAK/ND responses. For example, ATN may bedefined as ‘00001111’, ‘11110000’, ‘10101010’, ‘10110110’, ‘00110011’,or ‘01001001’. However, this is merely an example, and the ATN may beconfigured with various bit patterns.

Since the ATN bit pattern response generally informs the wireless powerreceiver that there is a message to be transmitted by the wireless powertransmitter, the wireless power receiver, upon receiving the ATN bitpattern response, transmits a DSR (poll) packet to the wireless powertransmitter to specifically recognize for what reason the wireless powertransmitter has sent the ATN bit pattern response (S2020).

In this case, the wireless power transmitter induces re-ping or powertransfer interruption (EPT) by transmitting a power-related requestpacket to the wireless power receiver in response to a DSR (poll) packet(S2025). This is to perform power calibration again according to thechange in coupling. Step S2025 corresponds to an operation requested bythe wireless power transmitter to the wireless power receiver so thatthe wireless power receiver stops re-ping or power transfer. As anexample, the power-related request packet is a packet transmitted by thewireless power transmitter to the wireless power receiver, and may alsobe referred to as an end power transfer request (EPTR) packet. In oneaspect, the end power transfer request packet may have the samestructure as the end power transfer (EPT) packet that the wireless powerreceiver transmits to the wireless power transmitter. For example, theend power transfer request packet may indicate the following values.

0x00—EPT/nul—use if none of the other codes is appropriate.

0x01—EPT/cc—charge complete; use to indicate that the battery is full.

0x02—EPT/if—internal fault; use if an internal logic error has beenencountered.

0x03—EPT/ot—over temperature; use if (e.g.) the battery temperatureexceeds a limit.

0x04—EPT/ov—over voltage; use if a voltage exceeds a limit.

0x05—EPT/oc—over current; use if the current exceeds a limit.

0x06—EPT/bf—battery failure; use if the battery cannot be charged.

0x08—EPT/nr—no response; use if the target operating point cannot bereached.

0x0A—EPT/an—aborted negotiation; use if a suitable Power TransferContract cannot be negotiated.

0x0B—EPT/rst—restart; use to restart the power transfer.

0x0C—EPT/rep—re-ping; use to restart the power transfer after aspecified delay (the re-ping delay).

Here, a value of the end power transfer request packet in thisembodiment may indicate restart or re-ping. Since an initiator ofre-ping or power transfer stop is the wireless power receiver, thewireless power transmitter cannot arbitrarily enter re-ping or powertransfer stop without permission of the wireless power receiver, andthus, a process of requesting re-ping or power transfer stop from thewireless power receiver which is an initiator of re-ping or powertransfer stop is predeterminatively performed as in step S2025.

The wireless power receiver receiving the request of re-ping orpower-related packet transmits ACK to the wireless power transmitter inresponse to the power-related request packet (S2030) and transmits thepower-related packet to the wireless power transmitter (S2035). Here,the power-related packet may be called a re-ping initiation packet. Asan example, the power-related packet may be an end power transfer (EPT)packet, and the EPT packet may be set to a value indicating re-ping(e.g., ‘0x0D’ or ‘0x0C’) or a value (e.g., ‘0x0B’) indicating restart ofpower transfer. Re-ping may be performed after a specific predeterminedre-ping delay. Here, the re-ping delay value may be set by, for example,a re-ping time (or delay) packet in a negotiation step (e.g., when thevalue of the EPT packet is ‘0x0C’). Alternatively, re-ping may beperformed immediately during a negotiation step despite a specificre-ping delay time preset by the re-ping time (or delay) packet (e.g.,in case where the value of the EPT packet=‘0x0D’ or ‘0x0E’).

When the power-related packet is received, the wireless powertransmitter resets the wireless power receiver according to the valueindicated by the power-related packet and performs Q measurement and FODagain (S2040). During the process of step S2040, the wireless powerreceiver may indicate that it is charging on a user interface althoughwireless power is not supplied to the wireless power receiver. The FODin step S2040 may correspond to the FOD operation before power transfer.If the wireless power transmitter fails to receive the power-relatedpacket within a certain time in step S2035, the wireless powertransmitter may reset the wireless power receiver and perform the entireFOD procedure again.

In this case, the wireless power transmitter may suppress a step oftransmitting an analog ping signal in the selection step and a step ofdetecting and identifying the wireless power receiver (a beep signalindicating detection/identification may be output here).

Here, power calibration may be performed again. In this case, in thepresent embodiment, the wireless power transmitter may include a step ofperforming FOD through Q measurement and new power calibration again.The new power calibration in this case may include the power calibrationdescribed in the embodiment of FIGS. 16 to 21. The new power calibrationof the wireless power transmitter may include a power calibrationoperation of the wireless power transmitter according to the embodimentsof FIGS. 16 to 21, and the new power calibration of the wireless powerreceiver may include a power calibration operation of the wireless powerreceiver according to the embodiment of FIGS. 16 to 21. Accordingly,additional power calibration according to the change in coupling iscompleted, and power calibration data such as the calibrated transmittedpower value and/or a calibrated received power value according to thenew power calibration may be derived.

The wireless power transmitter in the embodiments according to FIG. 22corresponds to the wireless power transmission device, the wirelesspower transmitter, or power transmission part disclosed in FIGS. 1 to15. Accordingly, the operation of the wireless power transmitter in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power transmitter in FIGS. 1 to 15. Forexample, in the present embodiment, the operation of transmittingwireless power to the wireless power receiver in the power transferphase according to step S2000 may be performed by the power conversionunit 110. In addition, the operation of receiving RPP, CEP, etc.,according to step S2005, the operation of detecting a change in couplingaccording to step S2010, the operation of transmitting a power-relatedrequest packet according to step S2025, the operation of receiving apower related packet according to step S2035, and the operation forperforming Q measurement and FOD according to S2040 may be performed bythe communication/control unit 120.

In addition, the wireless power receiver in the embodiment according toFIG. 22 corresponds to the wireless power reception device, the wirelesspower receiver, or the power reception part disclosed in FIGS. 1 to 15.Accordingly, the operation of the wireless power receiver in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power receiver in FIGS. 1 to 15. For example,in this embodiment, the operation of receiving wireless power from thewireless power transmitter in the power transfer phase according to stepS2000 may be performed by the power pickup unit 210. In addition, theoperation of generating and transmitting a packet such as RPP, CEP,etc., according to step S2005, the operation of detecting a change incoupling according to step S2010, the operation of receiving a powerrelated request packet according to step S2025, and the operation ofgenerating and transmitting a power related packet according to stepS2035 may be performed by the communication/control unit 220.

The power calibration method according to FIG. 22 is an example of acase where the wireless power receiver is an initiator of re-ping.Hereinafter, however, for instant re-ping, the wireless powertransmitter may be an initiator of re-ping. Accordingly, hereinafter, amethod of calibrating power when the initiator of re-ping is a wirelesspower transmitter is disclosed.

FIG. 23 is a flowchart illustrating a power calibration method based ona change in coupling according to another embodiment.

Referring to FIG. 23, steps S2100 to S2120 are the same as steps S2000to S2020, respectively. However, in the embodiment of FIG. 23, since thewireless power transmitter is an initiator of re-ping, the wirelesspower transmitter transmits a power-related packet instead of sending apower-related request packet to the wireless power receiver (S2125) andreceive ACK from the wireless power receiver (S2130) to enter the powercalibration phase. The power-related packet in step S2125 is, forexample, 1 byte (8 bits) and may have a format of a re-ping packet asshown in FIG. 24.

FIG. 24 shows a format of a re-ping packet according to an example.

Referring to FIG. 24, the re-ping packet may have a packet structureincluding reserved bits of 2 bits and a field (e.g., 6 bits) indicatingre-ping time information. The re-ping time information is a naturalnumber from 1 to 64 and is used to calculate the re-ping time Tre-ping.For example, the re-ping time may be Tre-ping=(ripping timeinformation)×0.2 s. Therefore, the re-ping time is 0.2 s, 0.4 s, . . . ,12.6 s. Of course, the number of bits included in the field indicatingthe reserved bit and the re-ping time may be variously modified.

Referring back to FIG. 23, the wireless power transmitter may performthe entire FOD procedure again (Q factor based FOD and APLD) to detect aforeign object or perform power calibration (S2135). The FOD in stepS2135 may correspond to the FOD operation before power transfer. As anexample, re-execution of the FOD procedure includes a process in whichthe wireless power transmitter removes power and restarts from Qmeasurement to a digital ping step. As another example, powercalibration includes an operation of updating the power calibration setbefore the change in coupling.

While re-ping is performed, the wireless power transmitter may suppressa step of transmitting an analog ping signal in the selection step and astep of detecting and identifying the wireless power receiver (a beepsignal indicating detection/identification may be output here).

If the wireless power receiver receives the digital ping signal earlieror later than the re-ping time, this may indicate that the wirelesspower receiver overlying the wireless power transmitter has beenreplaced by the user. Accordingly, the wireless power receiver mayperform a default UX (a message indicating a beep signal or initiationof wireless charging to the user).

The wireless power transmitter in the embodiments according to FIG. 23corresponds to the wireless power transmission device, the wirelesspower transmitter, or power transmission part disclosed in FIGS. 1 to15. Accordingly, the operation of the wireless power transmitter in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power transmitter in FIGS. 1 to 15. Forexample, in the present embodiment, the operation of transmittingwireless power to the wireless power receiver in the power transferphase according to step S2100 may be performed by the power conversionunit 110. In addition, the operation of receiving RPP, CEP, etc.,according to step S2105, the operation of detecting a change in couplingand/or insertion of a foreign object according to step S2110, theoperation of generating and transmitting a bit pattern responseaccording to step S2115, the operation of receiving a DSR packetaccording to step S2120, the operation of transmitting the power-relatedpacket according to step S2125, the operation of receiving the ACKresponse according to step S2130, and the operation of performing Qmeasurement and FOD or performing power calibration according to stepS2135 may be performed by the communication/control unit 120.

In addition, the wireless power receiver in the embodiment according toFIG. 23 corresponds to the wireless power reception device, the wirelesspower receiver, or the power reception part disclosed in FIGS. 1 to 15.Accordingly, the operation of the wireless power receiver in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power receiver in FIGS. 1 to 15. For example,in this embodiment, the operation of receiving wireless power from thewireless power transmitter in the power transfer phase according to stepS2100 may be performed by the power pickup unit 210. In addition, theoperation of generating and transmitting a packet such as RPP, CEP,etc., according to step S2105, the operation of receiving a bit patternresponse according to step S2115, the operation of generating andtransmitting a DSR packet according to step S2120, the operation ofreceiving the power-related packet according to step S2125, and theoperation of transmitting ACK according to S2130 may be performed by thecommunication/control unit 220.

Power Calibration Due to Load Change (2): using RP/3

FIG. 25 is a flowchart illustrating a method of performing powercalibration and FOD according to an embodiment.

Referring to FIG. 25, the wireless power receiver receives and measurestransmitted power (hereinafter, referred to as first light loadtransmitted power; Ptr_light) from the wireless power transmitter in alight-load condition and transmits a first received power packet (RPP)indicating a received power value under the light load condition to thewireless power transmitter (S2300). The first received power packet mayhave, for example, the format of FIG. 17. In addition, the mode fieldindicates a method for interpreting the received power value, and anexample of the mode field is shown in Table 5.

TABLE 5 Mode Indication contents ‘000’ Normal value; response requested‘001’ Light-load calibration value; response requested ‘010’Connected-load calibration value; response requested ‘011’ Multi-pointconnected-load calibration value, response requested ‘100’ Normal value;no response requested

Referring to Table 5, the mode field=‘000’ indicates that a receivedpower value is a normal power value (which may be indicated as RP/0),and the mode field=‘001’, ‘010’, and ‘011’ may indicate that thereceived power packet is related to power calibration (which may berepresented by RP/1, RP/2, and RP/3, respectively). That is, thewireless power receiver may indicate power calibration by transmitting areceived power packet having the mode field=‘001’, ‘010’, or ‘011’ tothe wireless power transmitter. Specifically, if the mode field=‘001’(i.e., RP/1), the received power packet may indicate a power value(hereinafter, referred to as a light-load calibration value, Prec_light)received by the wireless power receiver when the wireless power receiveris in the light-load condition. Also, if the mode field=‘010’ (i.e.,RP/2), the received power packet may indicate a power value(hereinafter, referred to as a connected-load calibration value,Prec_connected) received by the wireless power receiver when thewireless power receiver is in the connected-load condition. Also, if themode field=‘011’ (i.e., RP/3), it may indicate that the received powerpacket is related to a multi-point connected-load calibration value. Thelight load condition may refer to a condition in which a load (e.g., abattery) is not electrically connected to the wireless power receiver,and the connected-load condition may refer to a condition in which aload is connected to the wireless power receiver.

The wireless power transmitter and the wireless power receiver performinitial power calibration using RP/1 and RP/2 when entering the powertransfer phase. Thereafter, when the wireless power receiver increasesthe load power to RP/2 or greater, additional power calibration isrequired. Accordingly, the wireless power receiver transmits the RP/3 tothe wireless power transmitter, so that the wireless power transmittermay perform additional power calibration.

Here, the wireless power receiver may transmit an RP/3 packet foradditional power calibration to the wireless power transmitter when thewireless power transmitter supports an additional power calibration mode(e.g., WPC ver.1.3 or higher). Whether the wireless power transmittersupports additional power calibration may be confirmed, for example, bya version number of a standard supported by the wireless powertransmitter. That is, the WPC Qi wireless power transmitter may supportadditional power calibration only in ver.1.3 or higher.

Referring back to FIG. 25, since the first received power packetindicates the received power value (i.e., the light load calibrationvalue, Prec_light) measured under the light load condition, the modefield of the first received power packet is ‘001’ (i.e., RP/1).Therefore, step S2300 may further include a step in which the wirelesspower receiver sets the mode field=‘001’. When the mode field=‘010’ isconfirmed, the wireless power transmitter identifies that the receivedpower value indicated by the second received power packet is thelight-load calibration value (Prec_light). The wireless powertransmitter may store the light-load calibration value (Prec_light) inthe memory to perform power calibration. Although not shown, thewireless power transmitter may transmit an ACK or NAK to the wirelesspower receiver in response to the first received power packet. Also, thefirst received power packet may be transmitted multiple times orcontinuously. In this case, the first received power packet (i.e., RP/1)which is continuously transmitted may be treated as one received powerpacket (i.e., a single RP/1).

In one aspect, when receiving the RP/1, the wireless power transmittertransmits NAK until the wireless power receiver stably reaches thecorresponding power level (while monitoring the CE value), and when thepower level is stabilized, the wireless power transmitter transmits ACKand takes the RP1 value at that time.

The wireless power receiver receives and measures the firstconnected-load transmitted power (Ptr_connected (1)) from the wirelesspower transmitter under the first connected-load condition and thentransmits the second received power packet (i.e., RP/2) indicating thefirst connected-load calibration value (Prec_connected (1)) to thewireless power transmitter (S2305).

Step S2305 may further include a step in which the wireless powerreceiver sets the mode field=‘010’. When the mode field=‘010’ isconfirmed, the wireless power transmitter identifies that the receivedpower value indicated by the second received power packet is the firstconnected-load calibration value (Prec_connected (1)). The wirelesspower transmitter may store the first connected-load calibration value(Prec_connected (1)) in the memory to perform power calibration.

Power transfer characteristics or calibration curves according to FIG.18 and Equations 1 to 2 may be derived, for example, based on RP/1 andRP/2.

The wireless power receiver changes the connected-load (S2310). Thechange in the connected-load may include an increase or decrease in theconnected-load. The change in the connected-load may mean that a targetrectified voltage (target Vrec) or target power of the wireless powerreceiver increases or decreases compared to the previous connected-load.A situation in which the connected-load is changed may include a case inwhich the wireless power receiver uses multiple load steps to reach thetarget power. When the connected-load is changed, at least a part of thepreviously set power transfer characteristics may be changed, oradditional power transfer characteristics may be set, while maintainingthe previously set power transfer characteristics. For example, if thetransmitted power Ptr increases to a range where Ptr_connected (1)<Ptrdue to an increase in the connected-load, the power transfercharacteristic of FIG. 18 cannot cover this situation.

Accordingly, in order to reflect the state in which the connected-loadis changed in the power calibration and improve FOD performance, thewireless power transmitter and/or the wireless power receiver performmulti-point power calibration. To this end, the wireless power receiverreceives and measures the second connected-load transmitted power(Ptr_connected (2)) from the wireless power transmitter under the secondconnected-load condition, and then transmits a third received powerpacket RP/3 indicating the second connected-load calibration value(Prec_connected (2)) to the wireless power transmitter (S2315). When thewireless power transmitter responds with ACK to the second receivedpower packet RP/2 in step S2310, additional RP/2 transmission of thewireless power receiver may not be permitted. However, in order toimprove the power loss-based foreign object detection function, thelimitation on the timing of power calibration may be removed andmulti-point power calibration of two or more points may be required, andthus, the transmission of the third received power packet as in stepS2325 may be permitted.

Step S2325 may further include a step in which the wireless powerreceiver set the mode field to ‘011’ (mode field=‘011’). When it isconfirmed that the mode field=‘011’, the wireless power transmitteridentifies that the received power value indicated by the third receivedpower packet is a multi-point calibration value (Prec_connected (2)).Since the mode field=‘011’, the wireless power transmitter may know thatadditional power calibration is required.

As an example related to a transmission timing of RP/3, the transmissionof RP/3 may be performed at any time at which the wireless powerreceiver steps up the target load power. That is, initial powercalibration is performed based on RP/1 and RP/2 at the start of thepower transfer phase (according to steps S2300 to S2310), and after theinitial power calibration, multi-point power calibration may beperformed at any time at which the wireless power receiver graduallysteps up the target load power.

As another example related to a transmission timing of RP/3, thewireless power receiver may transmit RP/3 between a plurality of RP/0sor between a plurality of RP/0s and CEP in the power transfer phase.Here, the transmission of the RP/3 may be performed at any time at whichthe wireless power receiver steps up the target load power.

In order to perform multi-point power calibration, the wireless powertransmitter may store the second connected-load calibration value(Prec_connected (2)) in the memory.

Based on the power calibration data obtained through steps S2300, S2305,and S2325, power transfer characteristics may be derived or set. Thederived power transfer characteristics may be, for example, shown inFIG. 19 and Equations 3 to 6.

Regarding the power P_(transmitted) transmitted by the wireless powertransmitter, if the wireless power receiver receives a fourth receivedpower packet (i.e., RP/0) indicating a normal value (i.e., modefield=‘000’b) P_(received), rather than the received power packet (i.e.,mode field=‘001’b or ‘010b’) related to power calibration no longer,(S2330), the wireless power transmitter completes power calibration andperforms FOD based on the transmitted power P_(transmitted) and thereceived power P_(received) (S2335). For example, step S2335 may includea step in which the wireless power transmitter performs FOD based onpower loss according to FIG. 20.

Although not shown, the wireless power transmitter may transmit ACK orNAK to the wireless power receiver in response to RP/1, RP/2, and RP/3.The wireless power transmitter may repeat the operation of transmittingthe NAK to the wireless power receiver until control is achieved to atarget operating point. In addition, the wireless power receiver maytransmit one or more CE packet(s) between all received power packetsincluding RP/2, RP/2, and RP/3.

For example, according to the embodiment of FIG. 25, the wireless powerreceiver transmits the first received power packet RP/1 to the wirelesspower transmitter (S2300). However, if the corresponding power level isnot reached, the wireless power transmitter transmits the NAK to thewireless power receiver. In this case, the wireless power transmitterchecks one or more CE packet(s) transmitted from the wireless powerreceiver, while changing the operating point and determines whether thewireless power receiver has reached the target operating point. Thisprocess (RP/1 (NAK)-CE-CE-CE-CE-RP1 (NAK)-CE-CE-CE) is repeated, andwhen the power level is stable, the wireless power transmitter transmitsACK and takes the RP/1 value at that time as power calibration data.

When the ACK is received in response to the first received power packetRP/1, the wireless power receiver transmits the second received powerpacket RP/2 to the wireless power transmitter (S2305). However, if thecorresponding power level is not reached, the wireless power transmittertransmits NAK to the wireless power receiver. In this case, the wirelesspower transmitter checks one or more CE packet(s) transmitted from thewireless power receiver, while changing the operating points, anddetermines whether the wireless power receiver has reached a targetoperating point. The process (RP/2 (NAK)-CE-CE-CE-CE-RP2(NAK)-CE-CE-CE)is repeated and when the power level is stable, the wireless powertransmitter transmits ACK and takes the RP/2 value at that time as apower calibration parameter.

Thereafter, the wireless power receiver transmits the third receivedpower packet RP/3 to the wireless power transmitter according to achange in the connected-load (S2310) (S2325). However, if thecorresponding power level is not reached, the wireless power transmittertransmits NAK to the wireless power receiver. In this case, the wirelesspower transmitter checks one or more CE packet(s) transmitted from thewireless power receiver, while changing the operating points, anddetermines whether the wireless power receiver has reached a targetoperating point.

The process (RP/3(NAK)-CE-CE-CE-CE-RP3(NAK)-CE-CE-CE) is repeated andwhen the power level is stable, the wireless power transmitter transmitsACK and takes the RP/3 value at that time as power calibration data.

Thereafter, the wireless power receiver receives a received power packetindicating the normal value (i.e., mode field=‘000’b) Preceived, ratherthan the received power packet (i.e., mode field=‘001’b or ‘010b’)related to power calibration no longer, (S330), the wireless powertransmitter calibrates the Preceived based on the power calibration,calculates power loss, and performs FOD based on the power loss (S2335).

The wireless power transmitter in the embodiments according to FIG. 25corresponds to the wireless power transmission device, the wirelesspower transmitter, or power transmission part disclosed in FIGS. 1 to15. Accordingly, the operation of the wireless power transmitter in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power transmitter in FIGS. 1 to 15. Forexample, processing of power calibration, transmission of ACK/NAK,and/or reception of RP and CEP by the wireless power transmitter in theabove embodiments may be performed by the communication/control unit120.

In addition, the wireless power receiver in the embodiment according toFIG. 25 corresponds to the wireless power reception device, the wirelesspower receiver, or the power reception part disclosed in FIGS. 1 to 15.Accordingly, the operation of the wireless power receiver in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power receiver in FIGS. 1 to 15. For example,processing of power calibration, transmission of RP and CEP, and/orreception of ACK/NAK by the wireless power receiver in the aboveembodiments may be performed by the communication/control unit 220.

Another embodiment of the present disclosure includes a wireless powertransmitter and method and a wireless power receiver and method forperforming power calibration associated with an authenticationprocedure, That is, multi-point power calibration may be performed inassociation with authentication.

As an example, a method of performing multi-point power calibration fora wireless power receiver without an authentication function may includeperforming an initial power calibration using RP/1 and/or RP/2 at anintermediate power level (e.g., basic power profile (BPP or 5 W) whenthe wireless power transmitter and the wireless power receiver enter aninitial power transfer phase, performing power transfer at theintermediate power level by the wireless power transmitter, andcontinuously transmitting, by the wireless power receiver, the RP/3packet to the wireless power transmitter after the initial powercalibration to increase a load power to a target load power by stages.Here, the wireless power receiver may perform uncalibrated or partiallypower-calibrated FOD. In addition, the wireless power receiver maytransmit RP/0, while maintaining the power level.

As another example, a method of performing multi-point power calibrationfor a wireless power receiver without an authentication function mayinclude performing initial power calibration using RP/1 and/or RP/2 atan intermediate power level (e.g., basic power profile (BPP or 5 W) whenthe wireless power transmitter and the wireless power receiver entersthe initial power transfer phase, performing power transfer by thewireless power transmitter at the intermediate power level,transmitting, by the wireless power receiver, RP/0 to the wireless powertransmitter, while maintaining the target load power, and transmitting,by the wireless power receiver, an RP/3 packet to the wireless powertransmitter at any timing to increase the load power by stages. Here,the wireless power receiver may perform uncalibrated or partiallypower-calibrated FOD.

As another example, a method of performing multi-point power calibrationfor a wireless power receiver that performs an authentication functionincludes performing initial power calibration based on RP/1 and/or RP/2at an intermediate power level (i.e., BPP or 5 W) when the wirelesspower transmitter and the wireless power receiver enters the initialpower transfer phase, performing authentication by the wireless powertransmitter and/or the wireless power receiver transmits power at theintermediate power level, and transmitting, by the wireless powerreceiver, an RP/3 packet to the wireless power transmitter to increasethe load power by stages after authentication is successfully completed.Here, the step of performing authentication may further includeverifying whether authenticated (i.e., Qi-certified) extended powerprofile (EPP or 5 W or greater) is supported and making a contract forpower transfer at a desired target power value (i.e., 8 W or 15 W) whenauthentication is successfully performed as a result of theverification. Also, the wireless power receiver may transmit an RP/0packet to the wireless power transmitter during authentication.

Accordingly, the wireless power transmitter is controlled to performadditional power calibration. Here, the step of making the contract forpower transfer with the target power value (i.e. 8 W or 15 W) may beperformed in the renegotiation phase. That is, after the authenticationis completed and the renegotiation phase, the wireless power receivermay increase the target power. In this case, the wireless power receiverperforms additional power calibration by transmitting the RP/3 to thewireless power transmitter.

Power Calibration Due to Change in Coupling and/or FOD (2): UsingEPT/fod

When the wireless power transmitter performs FOD using the RP/0 value,the wireless power transmitter does not clearly distinguish between achange due to actual foreign object insertion and a change caused by theuser moving the wireless power receiver, and thus, the wireless powertransmitter may re-perform FOD using Q and a resonant value to stoppower transfer only when a foreign object is actually detected.

Accordingly, there is also a need for a method for preventing foreignobject misdetection by redoing pre-power FOD when a foreign object isinserted midway or coupling is changed. This method may be performedbased on an end power transfer (EPT) packet.

The method for performing FOD according to an embodiment includesmonitoring, by the wireless power transmitter and/or the wireless powerreceiver, a RP/0 and/or CEP, detecting, by the wireless powertransmitter and/or the wireless power receiver, the occurrence of aspecific event, transmitting, by the wireless power receiver, a EPTpacket (EPT/fod) for FOD to the wireless power transmitter, andperforming, by the wireless power transmitter, FOD based on the EPTpacket.

Here, the specific event includes, for example, a case where a foreignobject is inserted or a case where coupling is changed as the wirelesspower receiver is moved due to an external influence during the powertransfer phase.

The EPT packet for the FOD generated by the wireless power receiver maybe, for example, EPT/fod or EPT/rst or EPT/rep ((0x0B—EPT/rst—restart;use to restart the power transfer/0x0C—EPT/rep—re-ping; use to restartthe power transfer after a specified delay (the re-ping delay)). The EPTpacket for the FOD may have a structure as shown in FIG. 17 and mayindicate any one of the values in Table 6 below.

TABLE 6 > 0x00-EPT/nul-use if none of the other codes is appropriate.>0x01-Reserved> 0x02-EPT/if-internal fault; use if an internal logicerror has been encountered.> 0x03-EPT/ot-over temperature; use if (e.g.)the battery temperature exceeds a limit.> 0x04-EPT/ov-over voltage; useif a voltage exceeds a limit.> 0x05-EPT/oc-over current; use if thecurrent exceeds a limit.> 0x06-Reserved> 0x08-Reserved.> 0x0A-Reserved.>0x0B-EPT/rst-restart; use to restart the power transfer. NOTE Typically,a Power Transmitter engages in FOD after stopping the power transfer andbefore restarting it. For details about this procedure, see the QiSpecification, Foreign Object Detection.> 0x0C-EPT/rep-re-ping; use torestart the power transfer after a specified delay (the re-ping delay).NOTE A Power Receiver should use this End Power Transfer Code only if ithas verified that the Power Transmitter complies with version 1.3 orhigher of the Qi Specification.> EPT/rfid-RFID/NFC card; use if an RFID/NFC card has been detected> EPT/fod - Pre-power FOD and re-calibration

Here, the EPT/fod may indicate a reason for pre-power FOD and additionalpower calibration. That is, the wireless power receiver may use theEPT/fod value when the necessity of FOD and additional power calibrationbefore power transfer is recognized from internal observation. As anexample, the wireless power transmitter may determine a case ofsuspected foreign object insertion using a calibrated power value andthe wireless power receiver may suspect foreign object insertion when areceived power value or an operating point (e.g., rectified voltage)value is abnormally changed.

The EPT/rst may cause the wireless power transmitter and/or the wirelesspower receiver to cause noise due to restart and may give the user anundesirable experience. EPT/rep may be used To provide a better wirelesscharging service to the user. That is, the wireless power receiver maytransmit EPT/rep packets to the wireless power transmitter. In thiscase, the wireless power transmitter may further include measuring a Qfactor before power transfer (pre-power) and performing FOD through newpower calibration.

If the wireless power receiver uses EPT/rep, there is a problem that thewireless power transmitter cannot determine a time required forpre-power FOD. Therefore, it is necessary to define EPT/fod by a newcode of the EPT packet. In addition, the wireless power receivertransmits the EPT/fod packet to the wireless power transmitter so thatthe wireless power transmitter stops power transfer and performspre-power FOD. EPT/fod packets, like EPT/rep packets, are defined toprevent noise from occurring in the wireless power transmitter and/orthe wireless power receiver.

A method for performing FOD according to another embodiment includesmonitoring, by the wireless power transmitter and/or the wireless powerreceiver, a RP/0 and/or CEP, detecting, by the wireless powertransmitter and/or the wireless power receiver, the occurrence of aspecific event, transmitting, by the wireless power transmitter, an EPTpacket (EPT/fod) for FOD to the wireless power receiver, performing FOD,by the wireless power transmitter, based on the EPT packet, andre-starting power transfer according to the result of FOD.

In one aspect, the EPT packet for FOD generated by the wireless powertransmitter may have the same structure as the EPT packet for FODgenerated by the wireless power receiver as shown in FIG. 17. In thiscase, the EPT packet may indicate any one of the values in Table 7 below

TABLE 7 > 0x00-EPT/nul-use if none of the other codes is appropriate.>0x01-Reserved> 0x02-EPT/if-internal fault; use if an internal logicerror has been encountered.> 0x03-EPT/ot-over temperature; use if (e.g.)the battery temperature exceeds a limit.> 0x04-EPT/ov-over voltage; useif a voltage exceeds a limit.> 0x05-EPT/oc-over current; use if thecurrent exceeds a limit.> 0x06-Reserved> 0x08-Reserved.> 0x0A-Reserved.>0x0B-EPT/rst-restart; use to restart the power transfer. NOTE Typically,a Power Transmitter engages in FOD after stopping the power transfer andbefore restarting it. For details about this procedure, see the QiSpecification, Foreign Object Detection.> 0x0C-EPT/rep-re-ping; use torestart the power transfer after a specified delay (the re-ping delay).NOTE A Power Receiver should use this End Power Transfer Code only if ithas verified that the Power Transmitter complies with version 1.3 orhigher of the Qi Specification.> EPT/rfid-RFID/NFC card; use if an RFID/NFC card has been detected> EPT/fod - Pre-power FOD and re-calibration

For example, the EPT packet may indicate a specific value signifyingEPT/fod, and here, EPT/fod may indicate pre-power FOD and a reason foradditional power calibration. That is, the wireless power transmittermay use the EPT/fod value when the necessity of pre-power FOD and theadditional power calibration is recognized from internal observation.

In another aspect, the EPT packet for FOD generated by the wirelesspower transmitter may have a different structure from the EPT packet forFOD generated by the wireless power receiver. In this case, at leastsome of the values in Table 8 below indicating the EPT packet may bereused.

TABLE 8 > 0x00-EPT/nul-use if none of the other codes is appropriate.>0x01-Reserved> 0x02-EPT/if-internal fault; use if an internal logicerror has been encountered.> 0x03-EPT/ot-over temperature; use if (e.g.)the battery temperature exceeds a limit.> 0x04-EPT/ov-over voltage; useif a voltage exceeds a limit.> 0x05-EPT/oc-over current; use if thecurrent exceeds a limit.> 0x06-Reserved> 0x08-Reserved.> 0x0A-Reserved.>0x0B-EPT/rst-restart; use to restart the power transfer. NOTE Typically,a Power Transmitter engages in FOD after stopping the power transfer andbefore restarting it. For details about this procedure, see the QiSpecification, Foreign Object Detection.> 0x0C-EPT/rep-re-ping; use torestart the power transfer after a specified delay (the re-ping delay).NOTE A Power Receiver should use this End Power Transfer Code only if ithas verified that the Power Transmitter complies with version 1.3 orhigher of the Qi Specification.> EPT/rfid-RFID/NFC card; use if anRFID/NFC card has been detected> EPT/fod - Pre-power FOD andre-calibration

Meanwhile, before the step of transmitting, by the wireless powertransmitter, the EPT packet for FOD to the wireless power receiver, astep of transmitting, by the wireless power transmitter, ATN to thewireless power receiver, a step of transmitting, by the wireless powerreceiver, CEP to the wireless power transmitter, and a step oftransmitting, by the wireless power receiver, DSR/poll to the wirelesspower transmitter may be performed. In addition, upon receiving the EPTpacket for FOD, the wireless power receiver may transmit DSR/ACK to thewireless power transmitter.

Meanwhile, after restarting power transfer based on the EPT/fod packet,the wireless power transmitter and the wireless power receiver mayimmediately enter the power transfer phase if it is determined thatthere is no foreign object. The method of entering the power transferphase may be different depending on a case where the user wants to enterthe power transfer phase immediately after restarting and a case where afull protocol is to be performed. Specifically, the operation ofentering the power transfer phase may be defined as follows from thestandpoint of the wireless power receiver and the wireless powertransmitter.

First, the operation of the wireless power receiver is as follows.

As an example, the wireless power receiver may transmit RP/0 as a firstpacket to the wireless power transmitter when it is desired to enter thepower transfer phase immediately after restarting. After the restart,initial power calibration may be performed at the power transfer phase,and the previous power contract may be effectively preserved.

As another example, when attempting to perform a full protocol afterrestart, the wireless power receiver may transmit a signal strength (SS)packet as a first packet to the wireless power transmitter.

In this case, the wireless power receiver enters the power transferphase through a digital ping step, an identification and configurationstep, and a negotiation step after restarting. In addition, the wirelesspower receiver performs initial power calibration by transmitting RP/1and RP/2 at the start of power transfer, and thereafter, the wirelesspower receiver may perform additional power calibration by transmittingRP/3 each time the target load power is increased.

Next, the operation of the wireless power transmitter is as follows.

The wireless power transmitter may have a different procedure to enterthe power transfer phase according to an initial packet of the wirelesspower receiver.

As an example, when the wireless power transmitter receives a signalstrength (SS) packet as a first packet from the wireless power receiver,the wireless power transmitter performs a full protocol.

FIG. 26 is a flowchart illustrating a power calibration method based ona foreign object insertion or a change in coupling according to anembodiment.

Referring to FIG. 26, the wireless power transmitter transmits wirelesspower to the wireless power receiver in the power transfer phase(S2400). In the power transfer phase, the wireless power receivertransmits a received power packet (RPP) and a control error packet (CEP)to the wireless power transmitter (S2405).

The wireless power transmitter monitors information on power transmittedin the power transfer phase and/or information (or packet) received fromthe wireless power receiver and detects foreign object insertion or achange in coupling based on the monitoring result (S2410).

As an example, if the transmitted power (P_(transmitted)) is increaseddespite no increase in the received power, the wireless powertransmitter may determine that a coupling change event has occurred orthat a foreign object has been inserted.

As another example, after the control error (CE) converges to almost 0,if the CE is rapidly changed despite no intentional load change in thewireless power receiver, the wireless power transmitter may determinethat a coupling change event has occurred or that a foreign object hasbeen inserted. Here, the wireless power transmitter may determinewhether the change in the CE is due to an intentional change in the loadcondition of the wireless power receiver through the mode field of thereceived power packet (RPP). That is, the wireless power transmitter maydetermine whether a coupling change event occurs based on CEP and RPP.

When the change in coupling (or foreign object insertion) is detected instep S2410, the wireless power transmitter performs the entire FODprocedure again (Q factor-based FOD and APLD) to detect a foreign objector perform power calibration. Here, the power calibration includes anoperation of updating power calibration set before the change incoupling.

The wireless power transmitter may perform an operation of transmittinga specific bit pattern response to the wireless power receiver inresponse to the received power packet received in step S2405 in order toinform the wireless power receiver that a change in coupling hasoccurred (S2415).

FSK modulation may be used for transmission of the bit pattern response.For example, the bit pattern response is 8 bits and may be called ATN(attention) or RFC (request for communication). By setting the bitpattern response to a specific bit value and transmitting the same tothe wireless power receiver, the wireless power transmitter may requestthe wireless power receiver to transmit a DSR (Poll) packet or totransmit an EPT/fod packet.

As an example, an ACK response indicating a request approval may beindicated by a bit pattern of ‘11111111’, a NAK response rejecting arequest may be indicated by a bit pattern of ‘00000000’, and an NDresponse indicating an unrecognizable or invalid request may beindicated by a bit pattern of ‘01010101’. In addition, ATN may bedefined by various 8-bit sized bit patterns except for the bit patternsdefined for the above ACK/NAK/ND responses. For example, ATN may bedefined as ‘00001111’, ‘11110000’, ‘10101010’, ‘10110110’, ‘00110011’,or ‘01001001’. However, this is merely an example, and the ATN may beconfigured with various bit patterns.

Since the ATN bit pattern response generally informs the wireless powerreceiver that there is a message to be transmitted by the wireless powertransmitter, the wireless power receiver, upon receiving the ATN bitpattern response, transmits a DSR (poll) packet to the wireless powertransmitter to specifically recognize for what reason the wireless powertransmitter has sent the ATN bit pattern response (S2420).

Here, the wireless power transmitter transmits a packet requestingre-ping for Q factor measurement to the wireless power receiver inresponse to the DSR (poll) packet (S2425). This is to perform powercalibration again according to the change in coupling or foreign objectinsertion. Step S2425 corresponds to an operation requested by thewireless power transmitter to the wireless power receiver so that thewireless power receiver stops re-ping or power transfer.

The wireless power receiver receiving the packet requesting re-pingtransmits an end power transfer packet (EPT/fod) for FOD for Q factormeasurement to the wireless power transmitter (S2430). The EPT packetmay be set to a value (e.g., ‘0x0B’) indicating FOD or a valueindicating restart of power transfer.

When the EPT packet is received, the wireless power transmitter resetsthe wireless power receiver according to the value indicated by the EPTpacket and performs Q measurement and FOD (S2435). During the process ofstep S2435, the wireless power receiver may indicate that it is chargingon a user interface although wireless power is not supplied to thewireless power receiver. The FOD in step S2435 may correspond to thepre-power FOD operation. If the wireless power transmitter fails toreceive the EPT packet within a certain time in step S2430, the wirelesspower transmitter may reset the wireless power receiver and perform theentire FOD procedure again.

In this case, the wireless power transmitter may suppress a step oftransmitting an analog ping signal in the selection step and a step ofdetecting and identifying the wireless power receiver (a beep signalindicating detection/identification may be output here).

Here, power calibration may be performed again. In this case, in thepresent embodiment, the wireless power transmitter may include a step ofperforming FOD through Q measurement and new power calibration again.

The new power calibration in this case may include the power calibrationdescribed in the embodiment of FIGS. 16 to 21. The new power calibrationin this case may include the power calibration described in theembodiments of FIGS. 16 to 21. The new power calibration of the wirelesspower transmitter includes a power calibration operation of the wirelesspower transmitter according to the embodiments of FIGS. 16 to 21, andthe new power calibration of the wireless power reception deviceaccording to the embodiments of FIGS. 16 to 21 It may include a powercalibration operation of the wireless power receiver. Accordingly,additional power calibration according to the change in coupling iscompleted, and power calibration data such as a calibrated transmitpower value and/or a calibrated received power value according to thenew power calibration may be derived.

The wireless power transmitter in the embodiments according to FIG. 26corresponds to the wireless power transmission device, the wirelesspower transmitter, or power transmission part disclosed in FIGS. 1 to15. Accordingly, the operation of the wireless power transmitter in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power transmitter in FIGS. 1 to 15. Forexample, in the present embodiment, the operation of transmittingwireless power to the wireless power receiver in the power transfer stepaccording to step S2400 may be performed by the power conversion unit110. In addition, the operation of receiving RPP, CEP, etc., accordingto step S2405, the operation of detecting a change in coupling orforeign object insertion according to step S2410, the operation oftransmitting a re-ping request packet according to step S2425, theoperation of receiving an EPT packet according to step S2430, and theoperation for performing Q measurement and FOD according to S2435 may beperformed by the communication/control unit 120.

In addition, the wireless power receiver in the embodiment according toFIG. 26 corresponds to the wireless power reception device, the wirelesspower receiver, or the power reception part disclosed in FIGS. 1 to 15.Accordingly, the operation of the wireless power receiver in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power receiver in FIGS. 1 to 15. For example,in this embodiment, the operation of receiving wireless power from thewireless power transmitter in the power transfer step according to stepS2400 may be performed by the power pickup unit 210. In addition, theoperation of generating and transmitting a packet such as RPP, CEP,etc., according to step S2405, the operation of receiving a re-pingrequest packet according to step S2425, and the operation of generatingand transmitting the EPT packet according to step S2430 may be performedby the communication/control unit 220.

FIG. 27 is a flowchart illustrating a power calibration method based ona change in coupling or foreign object insertion according to anotherembodiment.

Referring to FIG. 27, steps S2500 to S2520 are the same as steps S2400to S2420, respectively. However, in the embodiment of FIG. 27, since thewireless power transmitter is an initiator of re-ping, the wirelesspower transmitter transmits an EPT packet instead of sending apower-related request packet to the wireless power receiver (S2425) andreceive ACK from the wireless power receiver (S2530) to enter the powercalibration phase.

In step S2525, the EPT packet for FOD generated by the wireless powerreceiver may be, for example, EPT/fod or EPT/rst or EPT/rep((0x0B—EPT/rst—restart; use to restart the powertransfer/0x0C—EPT/rep—re-ping; use to restart the power transfer after aspecified delay (the re-ping delay)). Here, the EPT/fod may indicate areason for pre-power FOD and additional power calibration. That is, thewireless power receiver may use the EPT/fod value when the necessity ofthe pre-power FOD and additional power calibration is recognized frominternal observation.

The EPT/rst may cause the wireless power transmitter and/or the wirelesspower receiver to cause noise due to restart and may give the user anundesirable experience. EPT/rep may be used To provide a better wirelesscharging service to the user. That is, the wireless power receiver maytransmit EPT/rep packets to the wireless power transmitter.

The wireless power transmitter may perform the entire FOD procedureagain (Q factor based FOD and APLD) to detect a foreign object orperform power calibration (S2535). As an example, re-execution of theFOD procedure includes a process in which the wireless power transmitterremoves power and restarts from Q measurement to a digital ping step. Asanother example, power calibration includes an operation of updating thepower calibration set before the change in coupling.

While re-ping is performed, the wireless power transmitter may suppressa step of transmitting an analog ping signal in the selection step and astep of detecting and identifying the wireless power receiver (a beepsignal indicating detection/identification may be output here).

If the wireless power receiver receives the digital ping signal earlieror later than the re-ping time, this may indicate that the wirelesspower receiver overlying the wireless power transmitter has beenreplaced by the user. Accordingly, the wireless power receiver mayperform a default UX (a message indicating a beep signal or initiationof wireless charging to the user).

The wireless power transmitter and the wireless power receiver mayrestart the power transfer based on the result of the FOD. Meanwhile,after restarting power transfer based on the EPT/fod packet, thewireless power transmitter and the wireless power receiver mayimmediately enter the power transfer phase if it is determined thatthere is no foreign object. The method of entering the power transferphase may be different depending on a case where the user wants to enterthe power transfer phase immediately after restarting and a case where afull protocol is to be performed. Specifically, the operation ofentering the power transfer phase may be defined as follows from thestandpoint of the wireless power receiver and the wireless powertransmitter.

First, the operation of the wireless power receiver is as follows.

As an example, the wireless power receiver may transmit RP/0 as a firstpacket to the wireless power transmitter when it is desired to enter thepower transfer phase immediately after restarting. After the restart,initial power calibration may be performed at the power transfer phase,and the previous power contract may be effectively preserved.

As another example, when attempting to perform a full protocol afterrestart, the wireless power receiver may transmit a signal strength (SS)packet as a first packet to the wireless power transmitter. After therestart, initial power calibration may be performed in the powertransfer phase and the previous power contract may be effectivelypreserved.

Next, the operation of the wireless power transmitter is as follows.

The wireless power transmitter may have a different procedure to enterthe power transfer phase according to an initial packet of the wirelesspower receiver.

As an example, when the wireless power transmitter receives a signalstrength (SS) packet as a first packet from the wireless power receiver,the wireless power transmitter performs a full protocol.

The wireless power transmitter in the embodiments according to FIG. 27corresponds to the wireless power transmission device, the wirelesspower transmitter, or power transmission part disclosed in FIGS. 1 to15. Accordingly, the operation of the wireless power transmitter in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power transmitter in FIGS. 1 to 15. Forexample, in the present embodiment, the operation of transmittingwireless power to the wireless power receiver in the power transfer stepaccording to step S2500 may be performed by the power conversion unit110. In addition, the operation of receiving RPP, CEP, etc., accordingto step S2505, the operation of detecting a change in coupling and/orforeign object insertion according to step S2510, the operation ofgenerating and transmitting a bit pattern response according to stepS2514, the operation of receiving the DSR packet according to stepS2520, the operation of transmitting EPT packet according to step S2525,the operation of receiving an ACK response according to step S2530, andthe operation for performing Q measurement and FOD according to S2535may be performed by the communication/control unit 120.

In addition, the wireless power receiver in the embodiment according toFIG. 27 corresponds to the wireless power reception device, the wirelesspower receiver, or the power reception part disclosed in FIGS. 1 to 15.Accordingly, the operation of the wireless power receiver in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power receiver in FIGS. 1 to 15. For example,in this embodiment, the operation of receiving wireless power from thewireless power transmitter in the power transfer step according to stepS2500 may be performed by the power pickup unit 210. In addition, theoperation of generating and transmitting a packet such as RPP, CEP,etc., according to step S2505, the operation of a bit pattern responseaccording to step S2515, the operation of generating and transmitting aDSR packet according to step S2520, the operation of receiving the EPTpacket according to step S2525, and the operation of transmitting ACKaccording to step S2530 may be performed by the communication/controlunit 220.

Hereinafter, a method of configuring a power calibration curve accordingto another embodiment will be described.

The power calibration curve should be able to represent a chargingprofile of the wireless power receiver. In one aspect, the powercalibration curve may include multiple segments. In another aspect, eachsegment of the power calibration curve may represent a charging profileof a specific power range at a specific operating point of the wirelesspower receiver.

Each segment of the power calibration curve may be represented by areceived power value of the wireless power receiver. For example, eachsegment of the power calibration curve may be represented by a powerlevel of the first received power RP/1, the second received power RP/2,and the third received power RP/3 of the wireless power receiver. In oneaspect, the initial calibration curve is based on two points. Here, thetwo points may be determined by the first received power RP/1 and thesecond received power RP/2. In another aspect, an extended calibrationcurve is based on multiple points of double points or greater. Here, themultiple points may be determined by at least two of the first receivedpower RP/1, the second received power RP/2, and the third received powerRP/3. That is, one or multiple third reception powers RP/3 may be usedto extend the initial calibration curve. In another aspect, arelationship of RP/1<=RP/2<=RP/3 may be established.

FIG. 28 is a power transfer characteristic or calibration curveaccording to another embodiment of the present disclosure.

Referring to FIG. 28, when the wireless power receiver operates in adifferent operating mode (e.g., when the wireless power receiveroperates at a different operating point), the wireless power receivermay transmit the first received power packet RP/1, the second receivedpower packet RP/2, and the third received power packet RP/3 to thewireless power transmitter. In other words, the wireless powertransmitter may receive the first received power packet RP/1, the secondreceived power packet RP/2, and the third received power packet RP/3from the wireless power receiver when the wireless power receiverchanges its operating points (op. points 1, 2, 3).

An example of a time point at which the wireless power receiver changesits operating point may include an initiation time point of the powertransfer phase. Another example of a time point at which the wirelesspower receiver changes its operating point may include a time point ofstepping up the operating point after renegotiation of the powertransfer contract (e.g., after successful authentication). Anotherexample of a time point at which the wireless power receiver changes itsoperating point may include a time point of stepping down the operatingpoint during the power transfer phase.

A format of the received power packet according to the presentembodiment may be the same as the format shown in FIG. 17. However, themode field may indicate 0 to 4 as shown in [Table 9] below, and thereceived power packets of modes ‘000’, ‘001’, ‘010’, ‘011’, and ‘100’are RP/It may be represented by RP/0, RP/1, RP/2, RP/3, and RP/4,respectively.

TABLE 9 Mode Indication contents ‘000’ Normal value; response requested‘001’ First calibration data point; response requested ‘010’ Secondcalibration data point or additional calibration data point; responserequested ‘011’ Extended calibration data point; response requested‘100’ Normal value; no response requested

Protocol for Initial Power Calibration

The wireless power transmitter and/or the wireless power receiver mayperform initial power calibration at each operating point using aplurality of received power packets. Here, the plurality of receivedpower values may include the first received power packet RP/1 and thesecond received power packet RP/2. Each time the operating point of thewireless power receiver is changed, the wireless power transmitterand/or the wireless power receiver may derive a new calibration curve bynew receiving power packets RP/1 and RP/2.

Specifically, the wireless power receiver transmits the first receivedpower packet RP/1 and the second received power packet RP/2 at the firstoperating point (op. point 1). After receiving the first received powerpacket RP/1 and the second received power packet RP/2, the wirelesspower transmitter constructs a first power calibration curve at thefirst operating point (op. point 1) based on the first received powerpacket RP/1 and the second received power packet RP/2. The first powercalibration curve becomes a first segment of the calibration curve.

Thereafter, the wireless power receiver transmits the first receivedpower packet RP/1 and the second received power packet RP/2 at thesecond operating point (op. point 2). After receiving the first receivedpower packet RP/1 and the second received power packet RP/2, thewireless power transmitter constructs a second power calibration curveat the second operating point (op. point 2) based on the first receivedpower packet RP/1 and the second received power packet RP/2. The secondpower calibration curve becomes a second segment of the calibrationcurve.

Thereafter, the wireless power receiver transmits the first receivedpower packet RP/1 and the second received power packet RP/2 at the thirdoperating point (op. point 3). After receiving the first received powerpacket RP/1 and the second received power packet RP/2, the wirelesspower transmitter constructs a third power calibration curve at thethird operating point (op. point 3) based on the first received powerpacket RP/1 and the second received power packet RP/2. The third powercalibration curve becomes a third segment of the calibration curve.

FIG. 28 shows an example in which the power calibration curves areconfigured at three operating points (op. points 1, 2, and 3),respectively, but as the operating points of the wireless power receiverare changed, three or more power calibration curves may be constructedor three or less power calibration curves may be constructed.

Protocol for Extending Initial Power Calibration Curve

The wireless power transmitter and/or the wireless power receiver mayderive an extended initial calibration curve at each operating pointusing the third received power packet RP/3.

The wireless power receiver may transmit a series of or multiple RP/3 tothe wireless power transmitter so that the wireless power transmittermay extend the power calibration curve, each time the initial powercalibration curve at the respective operating points (op. points 1, 2,and 3) needs to be extended.

Specifically, the wireless power receiver transmits the first receivedpower packet RP/1 and the second received power packet RP/2 at the firstoperating point (op. point 1) and the wireless power transmitterconstructs a first power calibration curve based on the first receivedpower packet RP/1 and the second received power packet RP/2, andthereafter, the wireless power receiver transmits the third receivedpower packet RP/3 to the wireless power transmitter. The wireless powertransmitter is configured to expand the first power calibration curvebased on the received third received power packet RP/3. The wirelesspower transmitter extends to a power calibration curve connecting thefirst power calibration curve to estimated received power values of thefirst received power packet RP/1 and the second received power packetRP/2 and connecting estimated received power values of the secondreceived power packet RP/2 and the third received power packet RP/3 (seeFIG. 17).

The wireless power receiver may transmit the third received power packetRP/3 to the wireless power transmitter even at the second operatingpoint (op. point 2) and/or the third operating point (op. point 3), andthe wireless power transmitter may extend the second power calibrationcurve and/or the third power calibration curve by receiving the thirdreceived power packet RP/3 according to each operating point.

According to an embodiment, the wireless power transmitter and/or thewireless power receiver may derive an extended initial calibration curveat each operating point using the second received power packet RP/2instead of the third received power packet RP/3. That is, each time theinitial power calibration curve at each operating point (op. point 1, 2,and 3) needs to be extended, the wireless power receiver additionallytransmits a series of or multiple RP/2 to the wireless power transmitterso that the wireless power transmitter may extend the power calibrationcurve.

According to an embodiment, the second received power packet RP/2 may bereferred to as an additional received power packet, and the thirdreceived power packet RP/3 may be referred to as an extended receivedpower packet.

FIG. 29 is a power transfer characteristic or calibration curveaccording to another embodiment of the present disclosure.

Referring to FIG. 29, a first segment (first power calibration curve) ofthe calibration curve may be defined by RP/1, RP/2, and RP/3. In oneaspect, the wireless power transmitter and/or wireless power receivermay use two points based on RP/1 and RP/2 to derive or calculate theinitial calibration curve of the first power calibration curve. Inanother aspect, the wireless power transmitter and/or wireless powerreceiver may use RP/3 to derive or calculate an extended calibrationcurve of the first power calibration curve. Here, one or multiple RP/3may be used to extend the initial calibration curve of the first powercalibration curve. In addition, a relationship of RP/1<=RP/2<=RP/3 maybe established.

A second segment of the calibration curve may be determined or definedby received power packets RP of a plurality of modes different from thereceived power packets RP used to determine the first segment. As anexample, a next segment of the calibration curve may be defined by afifth received power packet RP/5, a sixth received power packet RP/6,and a seventh received power packet RP/7. In one aspect, the wirelesspower transmitter and/or wireless power receiver may use two pointsbased on RP/5 and RP/6 to derive or calculate an initial calibrationcurve of the second segment (second power calibration curve). In anotheraspect, the wireless power transmitter and/or wireless power receivermay use the seventh received power packet RP/7 to derive or calculate anextended calibration curve of the second power calibration curve. Here,one or multiple seventh received power packets RP/7 may be used toextend the initial calibration curve of the second power calibrationcurve. In addition, a relationship of RP/5<=RP/6<=RP/7 may beestablished.

As shown in FIG. 29, the fifth received power packet RP/5, the sixthreceived power packet RP/6, and the seventh received power packet RP/7may be used to configure segments (power calibration curve) of the thirdsegment (third power calibration curve) or higher.

A format of the received power packet according to the presentembodiment may be the same as the format shown in FIG. 17. However, themode field may indicate 0 to 7 as shown in [Table 10] below, andreceived power packets of the modes ‘000’, ‘001’, ‘010’, ‘011’, ‘100’,‘101’, ‘110’, and ‘111’ may be represented by RP/0, RP/1, RP/2, RP/3,RP/4, RP/5, RP/6, and RP/7, respectively.

TABLE 10 Mode Indication contents ‘000’ normal value ‘001’ Firstcalibration data point of first segment of calibration curve ‘010’Second calibration data point of first segment of calibration curve‘011’ Extended calibration data point of first segment of calibrationcurve ‘100’ Normal value; no response requested ‘101’ First calibrationdata point of second segment of calibration curve ‘110’ Secondcalibration data point of second segment of calibration curve ‘111’Extended calibration data point of second segment of calibration curve

That is, when the wireless power receiver changes its operating point,the wireless power receiver may use a first received power packet set(RP/1, RP/2, RP/3) or a second received power packet set (RP/5, RP/6,RP/7). In other words, the wireless power transmitter may receive thefirst received power packet set (RP/1, RP/2, RP3) or the second set ofreceived power packets (RP/5, RP/6, RP/7) from the wireless powerreceiver when the wireless power receiver changes its operating points(op. Point 1, 2, 3). An example of a time point at which the wirelesspower receiver changes its operating point may include an initiationtime point of the power transfer phase. Another example of a time pointat which the wireless power receiver changes its operating point mayinclude a time point of stepping up the operating point afterrenegotiation of the power transfer contract (e.g., after successfulauthentication). Another example of a time point at which the wirelesspower receiver changes its operating point may include a time point ofstepping down the operating point during the power transfer phase.

Protocol for Initial Power Calibration

The wireless power transmitter and/or the wireless power receiver mayperform initial power calibration at each operating point using aplurality of received power packets. Here, the plurality of receivedpower values may include the first received power packet RP/1 and thesecond received power packet RP/2. Each time the operating point of thewireless power receiver is changed, the wireless power transmitterand/or the wireless power receiver may derive a new calibration curve bynew receiving power packets RP/5 and RP/6.

Specifically, the wireless power receiver transmits the first receivedpower packet RP/1 and the second received power packet RP/2 at the firstoperating point (op. point 1). After receiving the first received powerpacket RP/1 and the second received power packet RP/2, the wirelesspower transmitter constructs a first power calibration curve at thefirst operating point (op. point 1) based on the first received powerpacket RP/1 and the second received power packet RP/2. The first powercalibration curve becomes a first segment of the calibration curve.

Thereafter, the wireless power receiver transmits the fifth receivedpower packet RP/5 and the sixth received power packet RP/6 at the secondoperating point (op. point 2). After receiving the fifth received powerpacket RP/5 and the sixth received power packet RP/6, the wireless powertransmitter constructs a second power calibration curve at the secondoperating point (op. point 2) based on the first received power packetRP/1 and the second received power packet RP/2. The second powercalibration curve becomes a second segment of the calibration curve.

Thereafter, the wireless power receiver transmits the fifth receivedpower packet RP/5 and the sixth received power packet RP/6 at the thirdoperating point (op. point 3) again. After receiving the fifth receivedpower packet RP/5 and the sixth received power packet RP/6, the wirelesspower transmitter constructs a third power calibration curve at thethird operating point (op. point 3) based on the first received powerpacket RP/1 and the second received power packet RP/2. The third powercalibration curve becomes a third segment of the calibration curve.

FIG. 29 shows an example in which the power calibration curves areconfigured at three operating points (op. points 1, 2, and 3),respectively, but as the operating points of the wireless power receiverare changed, three or more power calibration curves may be configured orthree or less power calibration curves may be configured.

Protocol for Extending Initial Power Calibration Curve

The wireless power transmitter and/or the wireless power receiver mayderive an extended initial calibration curve at each operating pointusing the third received power packet RP/3 or the seventh received powerpacket RP/7. The wireless power receiver may transmit a series of ormultiple third received power packet RP/3 or the seventh received powerpacket RP/7 to the wireless power transmitter so that the wireless powertransmitter may extend the power calibration curve, each time theinitial power calibration curve at the respective operating points (op.points 1, 2, and 3) needs to be extended.

Specifically, the wireless power receiver transmits the first receivedpower packet RP/1 and the second received power packet RP/2 at the firstoperating point (op. point 1) and the wireless power transmitterconstructs a first power calibration curve based on the first receivedpower packet RP/1 and the second received power packet RP/2, andthereafter, the wireless power receiver transmits the third receivedpower packet RP/3 to the wireless power transmitter. The wireless powertransmitter is configured to expand the first power calibration curvebased on the received third received power packet RP/3. The wirelesspower transmitter extends to a power calibration curve connecting thefirst power calibration curve to estimated received power values of thefirst received power packet RP/1 and the second received power packetRP/2 and connecting estimated received power values of the secondreceived power packet RP/2 and the third received power packet RP/3 (seeFIG. 17).

The wireless power receiver may transmit the seventh received powerpacket RP/7 to the wireless power transmitter even at the secondoperating point (op. point 2) and/or the third operating point (op.point 3), and the wireless power transmitter may extend the second powercalibration curve and/or the third power calibration curve by receivingthe seventh received power packet RP/7 according to each operatingpoint.

According to an embodiment, the first received power packet RP/1 and thefifth received power packet RP/5 may be referred to as first receivedpower packets, the second received power packet RP/2 and the sixthreceived power packet RP/6 may be referred to as additional receivedpower packets, and the third received power packet RP/2 and the seventhreceived power packet RP/7 may be referred to as extended received powerpackets.

FIG. 30 is a power transfer characteristic or calibration curveaccording to another embodiment of the present disclosure.

Referring to FIG. 30, a first segment (first power calibration curve) ofthe calibration curve may be defined by RP/1, RP/2, and RP/3. In oneaspect, the wireless power transmitter and/or wireless power receivermay use two points based on RP/1 and RP/2 to derive or calculate theinitial calibration curve of the first power calibration curve. Inanother aspect, the wireless power transmitter and/or wireless powerreceiver may use RP/3 to derive or calculate an extended calibrationcurve of the first power calibration curve. Here, one or multiple RP/3may be used to extend the initial calibration curve of the first powercalibration curve. In addition, a relationship of RP/1<=RP/2<=RP/3 maybe established.

A next segment of the calibration curve may be determined or defined byRP/3. In one aspect, the wireless power transmitter and/or wirelesspower receiver may use two points based on two RP/3 to derive orcalculate the initial calibration curve. In another aspect, the wirelesspower transmitter and/or wireless power receiver may use additional RP/3to derive or calculate an extended calibration curve.

A format of the received power packet according to the presentembodiment may be the same as the format shown in FIG. 17. The modefield may be as shown in [Table 8].

After the wireless power transmitter constructs the extended first powercalibration curve by receiving the first received power packet RP/1, thesecond received power packet RP/2, and/or the third received powerpacket RP/3 from the wireless power receiver, the wireless powerreceiver may transmit the third received power packet RP/3 when changingits operating points. In other words, the wireless power transmitter mayreceive the third received power packet RP/3 from the wireless powerreceiver when the wireless power receiver changes its operating points(op. Point 1, 2, 3).

An example of a time point at which the wireless power receiver changesits operating point may include an initiation time point of the powertransfer phase. Another example of a time point at which the wirelesspower receiver changes its operating point may include a time point ofstepping up the operating point after renegotiation of the powertransfer contract (e.g., after successful authentication). Anotherexample of a time point at which the wireless power receiver changes itsoperating point may include a time point of stepping down the operatingpoint during the power transfer phase.

Protocol for Initial Power Calibration

The wireless power transmitter and/or the wireless power receiver mayperform initial power calibration at each operating point using aplurality of received power packets. Here, the plurality of receivedpower values may include the first received power packet RP/1 and thesecond received power packet RP/2. Each time the operating point of thewireless power receiver is changed, the wireless power transmitterand/or the wireless power receiver may derive a new calibration curve bynew receiving power packets RP/1 and RP/2.

Specifically, the wireless power receiver transmits the first receivedpower packet RP/1 and the second received power packet RP/2 at the firstoperating point (op. point 1). After receiving the first received powerpacket RP/1 and the second received power packet RP/2, the wirelesspower transmitter constructs a first power calibration curve at thefirst operating point (op. point 1) based on the first received powerpacket RP/1 and the second received power packet RP/2. The first powercalibration curve becomes a first segment of the calibration curve.

Thereafter, the wireless power receiver sequentially transmits two thirdreceived power packet RP/3 at the second operating point (op. point 2).After receiving the two third received power packets RP/3, the wirelesspower transmitter constructs a second power calibration curve at thesecond operating point (op. point 2) based on the received power packetsRP/3. The second power calibration curve becomes a second segment of thecalibration curve.

Thereafter, the wireless power receiver sequentially transmits two thirdreceived power packet RP/3 at the third operating point (op. point 3).After receiving the two third received power packets RP/3, the wirelesspower transmitter constructs a third power calibration curve at thethird operating point (op. point 3) based on the received power packetsRP/3. The third power calibration curve becomes a third segment of thecalibration curve.

FIG. 30 shows an example in which the power calibration curves areconfigured at three operating points (op. points 1, 2, and 3),respectively, but as the operating points of the wireless power receiverare changed, three or more power calibration curves may be configured orthree or less power calibration curves may be configured.

Protocol for Extending Initial Power Calibration Curve

The wireless power transmitter and/or the wireless power receiver mayderive an extended initial calibration curve at each operating pointusing the third received power packet RP/3.

The wireless power receiver may transmit a series of or multiple RP/3 tothe wireless power transmitter so that the wireless power transmittermay extend the power calibration curve, each time the initial powercalibration curve at the respective operating points (op. points 1, 2,and 3) needs to be extended.

Specifically, the wireless power receiver transmits the first receivedpower packet RP/1 and the second received power packet RP/2 at the firstoperating point (op. point 1) and the wireless power transmitterconstructs a first power calibration curve based on the first receivedpower packet RP/1 and the second received power packet RP/2, andthereafter, the wireless power receiver transmits the third receivedpower packet RP/3 to the wireless power transmitter. The wireless powertransmitter is configured to expand the first power calibration curvebased on the received third received power packet RP/3. The wirelesspower transmitter extends to a power calibration curve connecting thefirst power calibration curve to estimated received power values of thefirst received power packet RP/1 and the second received power packetRP/2 and connecting estimated received power values of the secondreceived power packet RP/2 and the third received power packet RP/3 (seeFIG. 17).

The wireless power receiver may transmit the third received power packetRP/3 to the wireless power transmitter even at the second operatingpoint (op. point 2) and/or the third operating point (op. point 3), andthe wireless power transmitter may extend the second power calibrationcurve and/or the third power calibration curve by receiving the thirdreceived power packet RP/3 according to each operating point.

According to an embodiment, the second received power packet RP/2 may bereferred to as an additional received power packet, and the thirdreceived power packet RP/3 may be referred to as an extended receivedpower packet.

Hereinafter, a method of constructing a power calibration curveaccording to another embodiment will be described.

FIG. 31 is a graph illustrating an initial power calibration curve.

Referring to FIG. 31, the wireless power receiver may wirelesslytransmit at least the first received power packet RP/1 and the secondreceived power packet RP/2 when constructing an initial calibrationcurve. In other words, the wireless power transmitter may receive atleast RP/1 and RP/2 from the wireless power receiver when the wirelesspower receiver constructs the initial calibration curve.

An example of a time point at which the wireless power receiverconstructs the initial calibration curve may include an initiation timepoint of the power transfer phase.

It is assumed that the x-axis and y-axis are a measured transmittedpower value (Pt(est)) and a measured received power value (Pr(est)),respectively, an actual transmitted power value is Pt, and an actualreceived power value is Pr. In this case, [Equation 7] below isestablished.

Pt(est)+δPt=Pt=Pr=Pr(est)−δPr

Here, δPt is an error between the actual transmitted power value and themeasured transmitted power value, and δPr may be an error between theactual received power value and the measured received power value. Thisis a case where a foreign object is not detected when pre-power FOD isused.

Based on [Equation 7], the calibrated power value (cal) may becalculated by [Equation 8] below.

(cal)=δPt+δPr=Pr(est)−Pt(est)   [Equation 8]

Therefore, when RP/1 and RP/2 are substituted into [Equation 8], thecalibrated power value may be expressed by [Equation 9], respectively.

P1(cal)=RP/1−Pt1(est)   [Equation 9]

P2(cal)=RP/2−Pt2(est)

FIG. 32 is a graph illustrating an extended power calibration curve.

Referring to FIG. 32, after the initial calibration curve is configuredbased on Equations 7 to 9, the wireless power transmitter and thewireless power receiver may extend the initial calibration curve basedon a changed event (e.g., change in operating points of the wirelesspower receiver). For example, when a specific event related to thewireless power receiver occurs, the wireless power receiver may transmitthe third received power packet RP/3 to the wireless power transmitter.Here, the wireless power transmitter may configure an extendedcalibration curve by extending the initial calibration curve using RP/3.In FIG. 32, it can be seen that the gradients of the calibration curvesbefore and after P2(cal) are changed. That is, the gradient beforeP2(cal) corresponds to the initial calibration curve and the gradientafter P2(cal) corresponds to the extended calibration curve.

When Equation 9 is applied to RP/3 as it is, an additional calibratedpower value may be derived as shown in Equation 10.

P3(cal)=RP/3−Pt3(est)   [Equation 10]

Meanwhile, by taking RP/3, which is located above the existing (orinitial) calibration curve section (or range), as a new calibrationpoint, foreign object detectability may be improved.

As an example, when the RP/3 exceeds the range of the existingcalibration curve, the existing calibration curve may be extended orchanged.

As another example, when the RP/3 is lower than the range of theexisting calibration curve, the existing calibration curve may bemaintained or pre-power FOD may be performed according to more detailedconditions.

For example, the wireless power transmitter may maintain the existingcalibration curve or perform pre-power FOD according to a result ofcomparing the Pfo derived by Equation 11 below and the threshold valueTH.

Pfo={Pt(est)+Pcal})−Pr(est)   [Equation 11]

When the Pfo is less than the threshold value, it is assumed that aforeign object does not exist and the wireless power transmitter and/orthe wireless power receiver may maintain the existing calibration curve.

Meanwhile, when the Pfo is greater than or equal to the threshold value,it is estimated that there is a high possibility of foreign object beingpresent, and the wireless power transmitter may perform an operation ofconfirming the existence of the foreign object by performing pre-powerFOD. A specific operation thereof is illustrated in FIG. 33.

FIG. 33 shows a method of performing FOD when Pfo is greater than orequal to a threshold value.

Referring to FIG. 33, the method includes transmitting, by the wirelesspower receiver, the third received power packet RP/3 (S2600),determining, by the wireless power transmitted which has received thethird received power packet RP/3, that Pfo is equal to or greater thanthe threshold value and transmitting an ATN pattern (S2610),transmitting, by the wireless power receiver, a CE packet to thewireless power transmitter (S2615), transmitting, by the wireless powerreceiver, a DSR (poll) packet to the wireless power transmitter (S2620),transmitting, by the wireless power transmitter which has received theDSR (poll) packet, an end power transfer (EPT) (PTx) packet forrequesting the wireless power receiver to transfer an EPT packet to thewireless power receiver in response to the DSR (poll) packet (S2630),and transmitting, by the wireless power receiver which has received theEPT (PTx) packet, to the wireless power transmitter (S2635).

When the EPT packet (EPT/rst or EPT/re-ping) is received from thewireless power receiver, the wireless power transmitter performspre-power FOD, and when it is determined that there is no foreign objectas a result of FOD detection, the wireless power transmitter may performre-ping so that recalibration may be performed in the power transferphase.

The EPT (PTx) packet of the wireless power transmitter may have the sameformat as the EPT packet of the wireless power receiver, and followingvalues of the EPT code may be used.

0x00—EPT/nul-use if none of the other codes is appropriate.

0x01—Reserved

0x02—EPT/if-PTx internal fault; use if an internal logic error has beenencountered.

0x03—EPT/ot-PTx over temperature; use if (e.g.) the battery temperatureexceeds a limit

0x04—EPT/ov-PTx over voltage; use if a voltage exceeds a limit.

0x05—EPT/oc-PTx over current; use if the current exceeds a limit.

0x06—Reserve

0x08—Reserved.

0x0A—Reserved.

0x0B—EPT/rst-PTx restart; use to restart the power transfer.

NOTE PTx engages in FOD after stopping the power transfer and beforerestarting it. For details about this procedure

0x0C—EPT/rep-PTx re-ping; use to restart the power transfer after aspecified delay (the re-ping delay).

NOTE. PTx should use this End Power Transfer Code only if it hasverified that the PRx complies with version 1.3 or higher of the QiSpecification.

EPT/rfid-RFID/NFC card; use if an RFID/NFC card has been detected by PTx

Hereinafter, a method of constructing a power calibration curveaccording to another embodiment will be described.

FIG. 34 is a graph illustrating a method of modeling a calibration curveaccording to an example.

Referring to FIG. 34, the wireless power transmitter constructs aninitial calibration curve (first power calibration curve) using a firstreceived power packet RP/1 and a second received power packet RP/2received from the wireless power receiver and constructs an updatedcalibration curve (second power calibration curve) by receiving aplurality of third received power packets RP/3 transmitted from thewireless power receiver while the wireless power receiver changes anoperating point from a first operating point (op. point 1) to a secondoperating point (op. point 2). The second received power packet RP/2 maybe referred to as an additional received power packet, and the thirdreceived power packet RP/3 may be referred to as an extended receivedpower packet.

FIG. 35 is a graph illustrating a method of modeling a calibration curveaccording to another example.

Referring to FIG. 35, the wireless power transmitter constructs aninitial calibration curve (first power calibration curve) using a firstreceived power packet RP/1 and a second received power packet RP/2received from the wireless power receiver and constructs an updatedcalibration curve (second power calibration curve) by receiving thefirst received power packet RP/1 and the second received power packetRP/2 retransmitted from the wireless power receiver while the wirelesspower receiver changes an operating point from a first operating point(op. point 1) to a second operating point (op. point 2). The secondreceived power packet RP/2 may be referred to as an additional receivedpower packet.

FIG. 36 is a view for explaining a method of constructing an initialcalibration curve according to an embodiment.

Referring to FIG. 36, in order to construct an initial calibrationcurve, the wireless power receiver may transmit the first received powerpacket RP/1 and the second received power packet RP/2. In other words,the wireless power transmitter may receive the first received powerpacket RP/1 and the second received power packet RP/2 from the wirelesspower receiver and construct an initial calibration curve based thereon.An example of a time point at which the wireless power receiverconfigures the initial calibration curve may include an initiation timepoint of the power transfer phase.

P(cal) (e.g., P1(cal) and/or P2(cal)) calculated based on Equation 7,Equation 8, Equation 9, etc., described in the embodiment of FIG. 31described above are negative numbers, the values may be set to zero.This is because if the P(cal) is negative, an erroneous FOD event may beincreased. Therefore, the initial calibration curve is configured in amanner that goes beyond an uncalibrated curve, so that it is possible tofurther improve detectability of a foreign object compared to theuncalibrated case.

According to FIG. 36, the initial calibration curve configured based onthe first received power packet RP/1 and the second received powerpacket RP/2 may be interpreted as a linear function of gradient a.

The gradient a may be expressed by Equation 12 below.

$\begin{matrix}{a = \frac{{\Pr\; 2({est})} - {\Pr\; 2({est})}}{{{Pt}\; 2({est})} - {{Pt}\; 1({est})}}} & \lbrack {{Equation}\mspace{14mu} 12} \rbrack\end{matrix}$

Meanwhile, when the wireless power transmitter identifies a danger ofthe foreign object using the calibration curve, the wireless powertransmitter needs to check the presence of a foreign object usingpre-power FOD.

The wireless power transmitter may calculate Pfo based on Equation 11described in the embodiment of FIG. 31 described above and estimate thepresence or absence of a foreign object based on the Pfo. As describedin the embodiment of FIG. 31, the wireless power transmitter comparesPfo with the threshold value TH. If Pfo is less than the thresholdvalue, the wireless power transmitter estimates that a foreign objectdoes not exist and if Pfo is greater than or equal to the thresholdvalue, the wireless power transmitter estimates that a foreign objectexists, and performs a protocol to perform FOD as shown in FIG. 33.

Meanwhile, a calibration time-out for initial calibration may bedefined. If the wireless power transmitter cannot transmit an ACKresponse within the calibration time-out for the second received powerpacket RP/2 received from the wireless power receiver, a power signalmay be removed. The calibration time-out may be defined, for example,within a range of 13.5±1.5 seconds.

After the initial calibration curve is constructed, the calibrationcurve may be updated in a specific situation.

As an example, the wireless power receiver may update a y-intercept ofthe calibration curve by transmitting only a single calibration point tothe wireless power transmitter using RP/3.

FIG. 37 shows a calibration curve obtained by updating the y-interceptof the initial calibration curve.

Referring to FIG. 37, when a specific event related to the wirelesspower receiver (e.g., a change in operating point) occurs, the wirelesspower receiver may transmit a third received power packet RP/3 to thewireless power transmitter. The wireless power transmitter may constructa new calibration curve by updating the y-intercept while maintainingthe gradient al of the initial calibration curve using the receivedsingle third received power packet RP/3. The wireless power receiver maycontinuously transmit the third received power packet RP/3 until ACK isreceived from the wireless power transmitter, and the wireless powertransmitter may construct a new calibration curve using the thirdreceived power packet RP/3 that has transmitted the ACK among the thirdreceived power packets RP/3 transmitted by the wireless power receiver.The third received power packet RP/3 may be referred to as an extendedreceived power packet.

When Equation 9 is applied to RP/3, an additionally calibrated powervalue (P3(cal)) may be derived as shown in Equation 10 described above.

As described above, in order to prevent an erroneous FOD event, ifP(cal) is negative, the value may be set to 0. Therefore, thecalibration curve updated by the third received power packet RP/3 isconfigured in a manner that exceeds the uncalibrated curve, so that itis possible to further improve detectability of a foreign objectcompared to the case where it is not calibrated.

The wireless power transmitter may calculate Pfo based on Equation 11described in the embodiment of FIG. 31 described above and estimate thepresence or absence of a foreign object based on Pfo. As described inthe embodiment of FIG. 31, the wireless power transmitter compares Pfowith the threshold value TH. If Pfo is less than the threshold value,the wireless power transmitter estimates that there is no foreignobject, and if Pfo is equal to or greater than the threshold value, thewireless power transmitter may estimate that there is a high possibilityof a foreign object being present and perform a protocol for performingFOD as shown in FIG. 33.

An example of configuring an updated calibration curve using a singlethird received power packet RP/3 has been described, but the updatedcalibration curve may be configured using the first received powerpacket RP/1 instead of the third received power packet RP/3. That is,when a specific event (e.g., a change in operating point) occurs, thewireless power receiver additionally transmits the first received powerpacket RP/1 to the wireless power transmitter and configures a newcalibration curve by updating the y-intercept, while maintaining thegradient a1 of the initial calibration curve, using the received firstreceived power packet RP/1.

An example of configuring an updated calibration curve using the singlethird received power packet RP/3 has been described, but the updatedcalibration curve may be configured using the second received powerpacket RP/2 instead of the third received power packet RP/3. That is,when a specific event (e.g., a change in operating point) occurs, thewireless power receiver additionally transmits the second received powerpacket RP/2 to the wireless power transmitter and configures a newcalibration curve by updating the y-intercept, while maintaining thegradient a1 of the initial calibration curve, using the received secondreceived power packet RP/2. The second received power packet RP/2 may bereferred to as an additional received power packet.

As another example, the wireless power receiver may update the gradientand the y-intercept of the calibration curve by transmitting a pluralityof consecutive calibration points to the wireless power transmitterusing RP/3.

FIG. 38 shows a calibration curve obtained by updating the gradient andy-intercept of the initial calibration curve.

Referring to FIG. 38, when a specific event (e.g., a change in operatingpoint) related to the wireless power receiver occurs, the wireless powerreceiver may transmit a plurality of consecutive third received powerpackets RP/3 to the wireless power transmitter. Here, the wireless powertransmitter may construct a new calibration curve by updating thegradient and y-intercept of the initial calibration curve using theplurality of third received power packets RP/3.

As shown in FIG. 38, the new calibration curves may be configured tohave a new gradient a2 and y intercept passing through (Pt3(1), RP3(1))and (Pt3(2), RP3(2)).

When Equation 9 is applied to RP/3, an additional calibrated power valueP3(cal) may be derived as shown in Equation 10 described above.

As described above, in order to prevent an erroneous FOD event, ifP(cal) is negative, the value may be set to 0. Therefore, thecalibration curve updated by the third received power packet RP/3 isconfigured in a manner that exceeds the uncalibrated curve, so that itis possible to further improve detectability of a foreign objectcompared to the case where it is not calibrated.

The wireless power transmitter may calculate Pfo based on Equation 11described in the embodiment of FIG. 31 described above and estimate thepresence or absence of a foreign object based on Pfo. As described inthe embodiment of FIG. 31, the wireless power transmitter compares Pfowith the threshold value TH. If Pfo is less than the threshold value,the wireless power transmitter estimates that there is no foreignobject, and if Pfo is equal to or greater than the threshold value, thewireless power transmitter may estimate that there is a high possibilityof a foreign object being present and perform a protocol for performingFOD as shown in FIG. 33.

Meanwhile, a calibration time-out for updating the calibration curve maybe defined.

The calibration time-out for updating the calibration curve may bedefined as a time required for the wireless power transmitter totransmit an ACK response for the third received power packet RP/3received next after the wireless power transmitter receives a firstthird received power packet RP/3 transmitted from the wireless powerreceiver to update the calibration curve. For example, the calibrationtime-out for updating the calibration curve may be defined within arange of 7±1.5 seconds.

An example of configuring the updated calibration curve using aplurality of third received power packets RP/3 has been described, butthe updated calibration curve may be configured using new first receivedpower packet RP/1 and second received power packet RP/2 instead of theplurality of third received power packets RP/3. That is, when a specificevent (e.g., a change in operating point) occurs, the wireless powerreceiver may additionally transmit the first received power packet RP/1and the second received power packet RP/2 to the wireless powertransmitter, and the wireless power transmitter may construct a newcalibration curve using the received new first received power packetRP/1 and the second received power packet RP/2. The second receivedpower packet RP/2 may be referred to as an additional received powerpacket.

In this case, the calibration time-out for updating the calibrationcurve may be defined as a time required for the wireless powertransmitter to transmit an ACK response for a second received powerpacket RP/2 received next after the wireless power transmitter receivesthe first received power packet RP/1 transmitted from the wireless powerreceiver to update the calibration curve.

The wireless power transmitter in the embodiment according to FIGS. 28to 38 corresponds to the wireless power transmission device, thewireless power transmitter, or power transmission part disclosed inFIGS. 1 to 15. Accordingly, the operation of the wireless powertransmitter in this embodiment is implemented by one or a combination oftwo or more of the components of the wireless power transmitter in FIGS.1 to 15. For example, the operation of receiving the received powerpacket from the wireless power receiver, the operation of constructing acalibration curve, and the like may be performed by thecommunication/control unit 120.

The wireless power receiver in the embodiments according to FIGS. 28 to38 corresponds to the wireless power reception device, the wirelesspower receiver, or power reception part disclosed in FIGS. 1 to 15.Accordingly, the operation of the wireless power receiver in thisembodiment is implemented by one or a combination of two or more of thecomponents of the wireless power transmitter in FIGS. 1 to 15. Forexample, the operation of transmitting the received power packet to thewireless power transmitter or the like may be performed by thecommunication/control unit 220.

Since the wireless power transmitting method and apparatus or thewireless power receiver and method according to an embodiment of thepresent disclosure do not necessarily include all the elements oroperations, the wireless power transmitter and method and the wirelesspower transmitter and method may be performed with the above-mentionedcomponents or some or all of the operations. Also, embodiments of theabove-described wireless power transmitter and method, or receivingapparatus and method may be performed in combination with each other.Also, each element or operation described above is necessarily performedin the order as described, and an operation described later may beperformed prior to an operation described earner.

The description above is merely illustrating the technical spirit of thepresent disclosure, and various changes and modifications may be made bythose skilled in the art without departing from the essentialcharacteristics of the present disclosure. Therefore, the embodiments ofthe present disclosure described above may be implemented separately orin combination with each other.

Therefore, the embodiments disclosed in the present disclosure areintended to illustrate rather than limit the scope of the presentdisclosure, and the scope of the technical spirit of the presentdisclosure is not limited by these embodiments. The scope of the presentdisclosure should be construed by claims below, and all technicalspirits within a range equivalent to claims should be construed as beingincluded in the right scope of the present disclosure.

What is claimed is:
 1. A wireless power receiver comprising: a powerpickup configured to receive, from a wireless power transmitter,wireless power generated based on magnetic coupling; and a controllerconfigured to: transmit, to the wireless power transmitter, a firstreceived power packet related to power calibration at a first operatingmode, transmit, to the wireless power transmitter, a second receivedpower packet related to power calibration at the first operating mode,transmit, to the wireless power transmitter, a third received powerpacket related to power calibration at a second operating mode, andtransmit, to the wireless power transmitter, a fourth received powerpacket related to power calibration at the second operating mode.
 2. Thewireless power receiver of claim 1, wherein the controller configured totransmit the second received power packet after receiving ACK from thewireless power transmitter in response to the first received powerpacket.
 3. The wireless power receiver of claim 2, wherein thecontroller configured to transmit a control error packet including acontrol error value and, receive the ACK from the wireless powertransmitter based on the control error value.
 4. The wireless powerreceiver of claim 1, wherein the controller configured to transmit thefourth received power packet after receiving ACK from the wireless powertransmitter in response to the third received power packet.
 5. Thewireless power receiver of claim 4, wherein the controller configured totransmit a control error packet including a control error value and,receive the ACK from the wireless power transmitter based on the controlerror value.
 6. The wireless power receiver of claim 1, wherein thefirst operating mode and the second operating mode have differentoperating points.
 7. The wireless power receiver of claim 1, whereineach of the first received power packet and the third received powerpacket includes information on a power value received by the wirelesspower receiver when the wireless power receiver is under a light loadcondition, and each of the second received power packet and the fourthreceived power packet includes information on a power values received bythe wireless power receiver when the wireless power receiver is under aconnected-load condition.
 8. The wireless power receiver of claim 1,wherein a value of a mode field included in the third received powerpacket is the same as a value of a mode field included in the firstreceived power packet, and a value of a mode field included in thefourth received power packet is the same as a value of a mode fieldincluded in the second received power packet.
 9. The wireless powerreceiver of claim 1, wherein a value of a mode field included in thethird received power packet is the same as a value of a mode fieldincluded in the fourth received power packet.
 10. A wireless powerreceiver comprising: a power pickup configured to receive, from awireless power transmitter, wireless power generated based on magneticcoupling; and a controller configured to: transmit, to the wirelesspower transmitter, a first received power packet of the first operatingmode related to power calibration, and transmit, to the wireless powertransmitter, a second received power packet of the first operating moderelated to power calibration, and transmit, to the wireless powertransmitter, a first received power packet of a second operating moderelated to power calibration, and transmit, to the wireless powertransmitter, a second received power packet of the second operating moderelated to power calibration, based on changing an operation mode fromthe first operation mode to the second operation mode.
 11. The wirelesspower receiver of claim 10, wherein the controller configured totransmit the second received power packet of the first operating modeafter receiving ACK from the wireless power transmitter in response tothe first received power packet of the first operating mode.
 12. Thewireless power receiver of claim 11, wherein the controller configuredto transmit a control error packet including a control error value and,receive the ACK from the wireless power transmitter based on the controlerror value.
 13. The wireless power receiver of claim 10, wherein thecontroller configured to transmit the second received power packet ofthe second operating mode after receiving ACK from the wireless powertransmitter in response to the first received power packet of the secondoperating mode.
 14. The wireless power receiver of claim 13, wherein thecontroller configured to transmit a control error packet including acontrol error value and, receive the ACK from the wireless powertransmitter based on the control error value.
 15. The wireless powerreceiver of claim 10, wherein the first operating mode and the secondoperating mode have different operating points.